Filed Pursuant to Rule 424(b)(3)
Registration No. 333-234080

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

Dear Stockholder of SemGroup Corporation:

On September 15, 2019, SemGroup Corporation (“SemGroup”) entered into an Agreement and Plan of Merger (the “merger agreement”) with Energy Transfer LP (“Energy Transfer”) and Nautilus Merger Sub LLC, a wholly owned subsidiary of Energy Transfer (“Merger Sub”), pursuant to which Merger Sub will merge with and into SemGroup (the “merger”), with SemGroup surviving the merger as a direct wholly owned subsidiary of Energy Transfer.

In the merger, SemGroup stockholders will receive, for each share of Class A Common Stock, par value $0.01 per share, of SemGroup (the “SemGroup common stock”) that they own as of immediately prior to the effective time of the merger (the “effective time”), a combination of (i) $6.80 in cash, without interest (the “per share cash amount”), and (ii) 0.7275 (the “exchange ratio”) of a common unit representing a limited partner interest in Energy Transfer (the “ET common units” and together with the per share cash amount, the “merger consideration”).

Each share of SemGroup Series A Cumulative Perpetual Convertible Preferred Stock, par value of $0.01 per share (the “SemGroup preferred stock”), outstanding immediately prior to the effective time will, at the election of the holders of a majority of such shares in accordance with the Certificate of Designations of Series A Cumulative Perpetual Convertible Preferred Stock of SemGroup, filed with the Secretary of State of the State of Delaware on January 19, 2018 (the “Certificate of Designations”), either (i) convert into shares of SemGroup common stock immediately prior to the effective time and receive the merger consideration, (ii) be exchanged for a “Substantially Equivalent Security” (as defined in the Certificate of Designations) of Energy Transfer or (iii) be redeemed by SemGroup for cash at a price per share of SemGroup preferred stock equal to 101% of the liquidation preference (as defined below).

Shares of SemGroup common stock are currently traded on the New York Stock Exchange (the “NYSE”) under the symbol “SEMG,” and ET common units are currently traded on the NYSE under the symbol “ET.”

In connection with the merger, SemGroup will hold a special meeting of its stockholders (the “special meeting”) to consider and vote on a proposal to approve and adopt the merger agreement (the “merger proposal”). The affirmative vote of the holders of a majority of the outstanding shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon at the special meeting is required to approve the merger proposal. At the special meeting, SemGroup stockholders will also vote on proposals to approve, on an advisory (non-binding) basis, the compensation that may be paid or become payable to SemGroup’s named executive officers in connection with the merger, which is not a condition to the merger (the “advisory compensation proposal”), and the adjournment of the special meeting, if necessary or appropriate, to solicit additional proxies if there are not sufficient votes cast at the special meeting to adopt the merger proposal (the “adjournment proposal”). Approval of the advisory compensation proposal will require the affirmative vote of a majority of the shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon and present in person or represented by proxy at the special meeting. Approval of the adjournment proposal will require the affirmative vote of a majority of the shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon and present in person or represented by proxy at the special meeting.

The special meeting will be held on December 4, 2019 at Two Warren Place, 5th Floor, 6120 South Yale Avenue, Tulsa, Oklahoma 74136, at 9:00 a.m. local time. Stockholders of record as of October 25, 2019 (the “record date”) are entitled to vote at the special meeting. The members of the SemGroup board unanimously recommend that SemGroup stockholders vote “FOR” the merger proposal, “FOR” the advisory compensation proposal and “FOR” the adjournment proposal.

In connection with the execution of the merger agreement, on September 15, 2019, SemGroup, Energy Transfer, Merger Sub and WP SemGroup Holdco, LLC, a holder of approximately 85.72% of the issued and outstanding shares of SemGroup preferred stock (“WP SemGroup”), which, on an as-converted basis, represents approximately 11.22% of the outstanding shares of SemGroup common stock as of the record date, entered into a support agreement (the “support agreement”). Pursuant to the support agreement, WP SemGroup agreed to, among other things, vote all of its shares in favor of adoption of the merger agreement and against alternative transactions and to elect to require SemGroup to redeem all of the SemGroup preferred stock at a cash purchase price per share equal to 101% of the liquidation preference thereof, which is generally calculated as $1,000 plus accrued and accumulated dividends on the preferred stock as adjusted in accordance with the Certificate of Designations (the “liquidation preference”) and which was $1,130.28 per share as of the record date. As a result, all shares of SemGroup preferred stock outstanding as of immediately prior to the effective time will be redeemed by SemGroup at a cash purchase price per share equal to 101% of the liquidation preference.

Your vote is very important. Information about the special meeting, the merger and the other business to be considered by the SemGroup stockholders at the special meeting is contained in the accompanying proxy statement/prospectus, which we urge you to read. In particular, see the section titled “Risk Factors” beginning on page 21 of the accompanying document.

The SemGroup board of directors has unanimously determined that the terms of the merger agreement and the transactions contemplated thereby, including the merger, are fair to, and in the best interests of, SemGroup and its stockholders, and recommends that the SemGroup stockholders vote in favor of the proposal to approve and adopt the merger agreement and the transactions contemplated thereby, including the merger.

Neither the U.S. Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued under the accompanying document or determined that the accompanying document is accurate or complete. Any representation to the contrary is a criminal offense.

The accompanying document is dated October 30, 2019 and is first being mailed to the SemGroup stockholders on or about October 31, 2019.

Dear Stockholder of SemGroup Corporation:

On December 4, 2019, SemGroup will hold a special meeting of stockholders (the “special meeting”) at Two Warren Place, 5th Floor, 6120 South Yale Avenue, Tulsa, Oklahoma 74136 at 9:00 a.m., local time. Only SemGroup stockholders of record at the close of business on October 25, 2019, the record date, are entitled to receive this notice and to vote at the special meeting or any adjournment or postponement of that meeting. The special meeting has been called for the following purposes:

The SemGroup board of directors has unanimously approved and adopted the merger agreement and is submitting the merger agreement to the SemGroup stockholders for approval and adoption at the special meeting. The merger agreement will be approved and adopted upon receiving the affirmative vote of the holders of a majority of the outstanding shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon at the special meeting.

Whether or not you plan to attend the special meeting, please submit your proxy with voting instructions as soon as possible. If you hold shares of SemGroup stock in your name as a stockholder of record, please complete, sign, date and return the accompanying proxy card in the enclosed self-addressed stamped envelope, use the toll-free telephone number shown on the proxy card or use the internet website shown on the proxy card. If you hold shares of SemGroup stock through a bank or broker, please use the voting instructions you have received from your bank or broker. Submitting your proxy will not prevent you from attending the special meeting and voting in person. Please note, however, that if you hold shares of SemGroup stock through a bank or broker, and you wish to vote in person at the special meeting, you must obtain from your bank or broker a proxy issued in your name.

You may revoke your proxy by attending the special meeting and voting your shares of SemGroup stock in person at the special meeting. You may also revoke your proxy at any time before it is voted by giving written notice of revocation to the Secretary of SemGroup at the address provided with the proxy card at or before the special meeting or by submitting a proxy with a later date.

Other sections of the proxy statement/prospectus describe the proposals listed above in more detail, as well as other matters contemplated in connection with the proposed merger. Before voting, please carefully read the proxy statement/prospectus in its entirety, including the merger agreement and all other annexes and including documents incorporated by reference, for further information relevant to the business to be transacted at the special meeting. In particular, see “Proposal 1: The Merger,” beginning on page 34, for a description of the transactions contemplated by the merger agreement, and “Risk Factors,” beginning on page 21, for an explanation of the risks associated with the merger and the other transactions contemplated by the merger agreement.

SemGroup’s board of directors (the “SemGroup board of directors”) has (i) determined that the merger agreement and the transactions contemplated thereby, including the merger, are fair to, and in the best interests of SemGroup and its stockholders, (ii) approved and declared advisable the merger agreement and the transactions contemplated thereby, including the merger, (iii) approved the execution, delivery and performance by SemGroup of the merger agreement and the consummation of the transactions contemplated thereby, including the merger, (iv) resolved to recommend adoption of the merger agreement by SemGroup’s stockholders and (v) directed that the merger agreement be submitted to the stockholders of SemGroup for its adoption.

The SemGroup board of directors recommends that the SemGroup stockholders vote:

A complete list of registered SemGroup stockholders entitled to vote at the special meeting will be available for inspection at the principal place of business of SemGroup at Two Warren Place, 6120 South Yale Avenue, Suite 1500, Tulsa, Oklahoma 74136, during regular business hours for a period of no less than ten days before the special meeting and at the place of the special meeting during the special meeting.

YOUR VOTE IS VERY IMPORTANT, REGARDLESS OF THE NUMBER OF SHARES THAT YOU OWN. The merger between Energy Transfer and SemGroup cannot be completed without the adoption of the merger proposal by the affirmative vote of the holders of a majority of the outstanding shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon at the special meeting.

If you have any questions concerning the merger or the other transactions contemplated by the merger agreement or the accompanying proxy statement/prospectus or would like additional copies, please contact SemGroup’s proxy solicitor:

D.F. King & Co., Inc.

48 Wall Street, 22nd Floor

New York, New York 10005

Email: SEMG@dfking.com

Stockholders may call toll free: (866) 207-3626

Banks and Brokers may call collect: (212) 269-5550

October 30, 2019

ADDITIONAL INFORMATION

This document, which forms part of a registration statement on Form S-4 filed with the U.S. Securities and Exchange Commission (the “SEC”), constitutes a proxy statement of SemGroup under Section 14(a) of the U.S. Securities Exchange Act of 1934, as amended (the “Exchange Act”), with respect to the solicitation of proxies for the special meeting of stockholders of SemGroup, or any adjournment or postponement thereof, to, among other things, approve and adopt the merger agreement and the transactions contemplated thereby. This document is also a prospectus of Energy Transfer under Section 5 of the U.S. Securities Act of 1933, as amended (the “Securities Act”), for ET common units that will be issued to stockholders of SemGroup in the merger pursuant to the merger agreement.

As permitted under the rules of the SEC, this document incorporates by reference important business and financial information about Energy Transfer and SemGroup from other documents filed with the SEC that are not included in or delivered with this document. Please read the section titled “Where You Can Find More Information.” You can obtain any of the documents incorporated by reference into this document from the SEC’s website at www.sec.gov. This information is also available to you without charge upon your request in writing or by telephone from Energy Transfer or SemGroup at the following addresses and telephone numbers:

Please note that copies of the documents provided to you will not include exhibits, unless the exhibits are specifically incorporated by reference into the documents or this document.

You may obtain certain of these documents at Energy Transfer’s website, www.energytransfer.com, and at SemGroup’s website, www.semgroup.com. None of the information contained on the website of Energy Transfer or SemGroup is incorporated by reference into this document.

In order to receive timely delivery of the documents in advance of the special meeting, your request should be received no later than November 26, 2019. If you request any documents, Energy Transfer or SemGroup will mail them to you by first class mail, or another equally prompt means, within one business day after receipt of your request.

If you have any questions about the merger or the consideration that you will receive in connection with the merger, including any questions relating to the transmittal of materials, or would like additional copies of the letter of transmittal (which is being mailed to SemGroup stockholders separately), you may contact SemGroup’s proxy solicitor at the address and telephone number listed below. You will not be charged for any additional letters of transmittal that you request.

The Solicitation Agent for the Special Meeting is:

D.F. King & Co., Inc.

48 Wall Street, 22nd Floor

New York, New York 10005

Email: SEMG@dfking.com

You may obtain information regarding the Special Meeting

from the Solicitation Agent as follows:

Stockholders may call toll free: (866) 207-3626

Banks and Brokers may call collect: (212) 269-5550

CONTENTS

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QUESTIONS AND ANSWERS ABOUT THE MERGER AND SPECIAL MEETING

Set forth below are questions that you, as a stockholder of SemGroup, may have regarding the merger and the special meeting of SemGroup stockholders and brief answers to those questions. For a more complete description of the legal and other terms of the merger, please read this entire document, including the merger agreement, which is attached as Annex A to this proxy statement/prospectus, and the documents incorporated by reference into this document. You may obtain a list of the documents incorporated by reference into this document in the section “Where You Can Find More Information.”

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RISK FACTORS

In addition to the other information included and incorporated by reference into this document, including the matters addressed in the section titled “Cautionary Statement Regarding Forward-Looking Statements,” you should carefully consider the following risks before deciding whether to vote for the approval and adoption of the merger agreement and the transactions contemplated thereby. In addition, you should read and consider the risks associated with each of the businesses of Energy Transfer and SemGroup. These risks can be found in Energy Transfer’s and SemGroup’s respective Annual Reports on Form 10-K for the year ended December 31, 2018, as updated by subsequent Quarterly Reports on Form 10-Q, all of which are filed with the SEC and incorporated by reference into this proxy statement/prospectus. For further information regarding the documents incorporated into this document by reference, please see the section titled “Where You Can Find More Information.” Realization of any of the risks described below, any of the events described under “Cautionary Statement Regarding Forward-Looking Statements” or any of the risks or events described in the documents incorporated by reference could have a material adverse effect on Energy Transfer’s, SemGroup’s or the combined company’s business, financial condition, cash flows and results of operations and could result in a decline in the trading prices of their respective common units or common stock.

Risks Factors Related to the Merger

Because the market price of ET common units will fluctuate prior to the consummation of the merger, SemGroup stockholders cannot be sure of the market value of ET common units that they will receive in the merger.

At the time the merger is completed, SemGroup stockholders will receive, for each share of SemGroup common stock they own as of immediately prior to the merger, a combination of $6.80 in cash and 0.7275 of an ET common unit. At the time that SemGroup stockholders cast their votes regarding approval of the merger agreement and the merger, SemGroup stockholders will not know the actual market value of the ET common units that they will receive when the merger is finally completed. The actual market value of the ET common units, when received by SemGroup common stockholders, will depend on the market value of those units on that date. This market value may be less than the value of the ET common units on the date of the merger agreement and on the date that SemGroup stockholders vote on the merger agreement. These fluctuations in the market value of ET common units may be caused by changes in the businesses, operations, results and prospects of both Energy Transfer and SemGroup, market expectations of the likelihood that the merger will be completed and the timing of the completion, general market and economic conditions or other factors.

The merger is subject to various closing conditions, and any delay in completing the merger may reduce or eliminate the benefits expected and delay the payment of the merger consideration to SemGroup’s common stockholders.

The merger is subject to the satisfaction of a number of other conditions beyond the parties’ control that may prevent, delay or otherwise materially adversely affect the completion of the merger. These conditions include, among other things, SemGroup stockholder approval and the expiration or termination of any applicable waiting period under the HSR Act. Energy Transfer and SemGroup cannot predict with certainty whether and when any of these conditions will be satisfied. Any delay in completing the merger could cause the combined company not to realize, or delay the realization, of some or all of the benefits that the companies expect to achieve from the merger. In such context, the date on which SemGroup’s common stockholders will receive the merger consideration is also uncertain.

Certain executive officers and directors of SemGroup have interests in the merger that are different from, or in addition to, the interests of SemGroup stockholders generally, which could have influenced their decision to support or approve the merger.

Certain executive officers and directors of SemGroup are parties to agreements or participants in other arrangements that give them interests in the merger that may be different from, or be in addition to, your interests

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as a stockholder of SemGroup. You should consider these interests in voting on the merger. We have described these different interests under “Proposal 1: The Merger – Interests of SemGroup’s Directors and Executive Officers in the Merger.”

The merger agreement limits SemGroup’s ability to pursue alternatives to the merger.

The merger agreement contains provisions that make it more difficult for SemGroup to sell its business to a party other than Energy Transfer. These provisions include the general prohibition on SemGroup soliciting any acquisition proposal (as defined in the section titled “The Merger Agreement – Non-Solicitation by SemGroup”) or offer for a competing transaction from a third party, and the requirement that SemGroup pay Energy Transfer a breakup fee of $54.5 million or up to $27.25 million of Energy Transfer’s expenses if the merger agreement is terminated in specified circumstances, including in the event SemGroup terminates the merger agreement in response to an acquisition proposal from a third party that the SemGroup board of directors determines constitutes a superior offer. In addition, even if the SemGroup board of directors receives a superior offer, it must, prior to accepting any offer from a competing bidder, provide Energy Transfer with the opportunity to amend the merger agreement such that the third-party offer no longer constitutes a superior offer. See “The Merger Agreement – Termination of the Merger Agreement” and “The Merger Agreement – Breakup Fee and Energy Transfer Expenses.” The foregoing may discourage a third party that might have an interest in acquiring all or a significant part of SemGroup from considering or proposing an acquisition, even if that party were prepared to pay consideration with a higher per share value than the current proposed merger consideration.

Furthermore, the breakup fee and the Energy Transfer expense reimbursement provisions may result in a potential competing acquiror proposing to pay a lower per share price to acquire SemGroup than it might otherwise have proposed to pay.

SemGroup’s financial estimates are based on various assumptions that may not prove to be correct.

The financial estimates set forth in the forecast included under “Proposal 1: The Merger – SemGroup Unaudited Prospective Financial Information” are based on assumptions of, and information available to, SemGroup at the time they were prepared and provided to the SemGroup board of directors and its financial advisors. SemGroup cannot know whether such assumptions will prove correct. Any or all of such estimates may turn out to be wrong. Such estimates can be adversely affected by inaccurate assumptions or by known or unknown risks and uncertainties, many of which are beyond Energy Transfer’s and SemGroup’s control. Many factors mentioned in this proxy statement/prospectus, including the risks outlined in this “Risk Factors” section and the events or circumstances described under “Cautionary Statement Regarding Forward-Looking Statements,” will be important in determining Energy Transfer’s and SemGroup’s future results. As a result of these contingencies, actual future results may vary materially from SemGroup’s estimates. In view of these uncertainties, the inclusion of SemGroup’s financial estimates in this proxy statement/prospectus is not and should not be viewed as a representation that the forecast results will be achieved.

SemGroup’s financial estimates were not prepared with a view toward public disclosure, and such financial estimates were not prepared with a view toward compliance with published guidelines of any regulatory or professional body. Further, any forward-looking statement speaks only as of the date on which it is made, and Energy Transfer and SemGroup undertake no obligation, other than as required by applicable law, to update the financial estimates herein to reflect events or circumstances after the date those financial estimates were prepared or to reflect the occurrence of anticipated or unanticipated events or circumstances.

The financial estimates included in this proxy statement/prospectus have been prepared by, and are the responsibility of, SemGroup alone. Moreover, neither SemGroup’s independent accountants, Grant Thornton LLP, nor any other independent accountants, have compiled, examined or performed any procedures with respect to SemGroup’s prospective financial information contained herein, nor have they expressed any opinion or any other form of assurance on such information or its achievability, and, accordingly, Grant Thornton LLP assumes

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no responsibility for, and disclaims any association with, SemGroup’s prospective financial information. The reports of Grant Thornton LLP incorporated by reference herein relate exclusively to the historical financial information of the entities named in those reports and do not cover any other information in this proxy statement/prospectus and should not be read to do so. See “Proposal 1: The Merger – SemGroup Unaudited Prospective Financial Information.”

A different set of factors and conditions affect ET common units and could have a negative impact on the unit price.

Upon completion of the merger, SemGroup common stockholders who receive ET common units will become equityholders in Energy Transfer. The businesses of Energy Transfer and the other companies it has acquired and may acquire in the future are different in many respects from those of SemGroup. There is a risk that various factors, conditions and developments which would not affect the price of SemGroup’s common stock could negatively affect the price of ET common units. Please see the section titled “Cautionary Statement Regarding Forward-Looking Statements” for a summary of some of the key factors that might affect Energy Transfer and the prices at which ET common units may trade from time to time. SemGroup stockholders are also urged to read carefully the risk factors included in Energy Transfer’s Annual Report on Form 10-K for the year ended December 31, 2018 and any subsequent Quarterly Reports on Form 10-Q, which are incorporated by reference into this document.

SemGroup common stockholders will have a reduced ownership and voting interest after the merger and will exercise less influence over management.

SemGroup common stockholders currently have the right to vote in the election of the SemGroup board of directors and other matters affecting SemGroup. When the merger occurs, each SemGroup common stockholder will become a unitholder of Energy Transfer with a percentage ownership of the combined company that is much smaller than such stockholder’s percentage ownership of SemGroup. Based on the number of ET common units and shares of SemGroup common stock outstanding as of October 25, 2019, SemGroup common stockholders will own approximately 2.2% of the outstanding ET common units after the merger. Energy Transfer unitholders are not entitled to elect the directors of Energy Transfer’s general partner. In addition, Energy Transfer unitholders have only limited voting rights on matters affecting Energy Transfer’s business and, therefore, limited ability to influence management’s decisions regarding its business. Because of this, SemGroup common stockholders will have less influence on the management and policies of Energy Transfer than they have now on the management and policies of SemGroup.

ET common units to be received by SemGroup common stockholders as a result of the merger will have different rights from SemGroup common stock.

Following completion of the merger, SemGroup common stockholders will no longer hold shares of SemGroup common stock, but will instead be unitholders of Energy Transfer. There are important differences between the rights of SemGroup stockholders and the rights of Energy Transfer unitholders. See “Comparison of Rights of Energy Transfer Common Unitholders and SemGroup Common Stockholders” for a discussion of the different rights associated with SemGroup common stock and ET common units.

If the merger agreement is terminated, under certain circumstances, SemGroup may be obligated to reimburse Energy Transfer for costs incurred related to the merger or pay a breakup fee to Energy Transfer. These costs could require SemGroup to seek loans or use SemGroup’s available cash that would have otherwise been available for operations, dividends or other general corporate purposes.

In certain circumstances, SemGroup would be responsible for reimbursing Energy Transfer for up to $27.25 million in expenses related to the transaction or may be obligated to pay a breakup fee to Energy Transfer of $54.5 million. If the merger agreement is terminated, the breakup fee required to be paid, if any, by SemGroup

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under the merger agreement may require SemGroup to seek loans or borrow amounts to enable it to pay these amounts to Energy Transfer. In either case, payment of these amounts would reduce the cash SemGroup has available for operations, dividends or other general corporate purposes. See “The Merger Agreement – Breakup Fee and Energy Transfer Expenses.”

The failure to successfully combine the businesses of Energy Transfer and SemGroup in the expected time frame may adversely affect Energy Transfer’s future results, which may adversely affect the value of the ET common units that SemGroup stockholders would receive in the merger.

The success of the merger will depend, in part, on the ability of Energy Transfer to realize the anticipated benefits from combining the businesses of Energy Transfer and SemGroup. To realize these anticipated benefits, Energy Transfer’s and SemGroup’s businesses must be successfully combined. If the combined company is not able to achieve these objectives, the anticipated benefits of the merger may not be realized fully or at all or may take longer to realize than expected. In addition, the actual integration may result in additional and unforeseen expenses, which could reduce the anticipated benefits of the merger.

Energy Transfer and SemGroup, including their respective subsidiaries, have operated and, until the completion of the merger, will continue to operate independently. It is possible that the integration process could result in the loss of key employees, as well as the disruption of each company’s ongoing businesses or inconsistencies in their standards, controls, procedures and policies. Any or all of those occurrences could adversely affect the combined company’s ability to maintain relationships with customers and employees after the merger or to achieve the anticipated benefits of the merger. Integration efforts between the two companies will also divert management attention and resources. These integration matters could have an adverse effect on each of Energy Transfer and SemGroup.

The pendency of the merger could materially adversely affect the future business and operations of SemGroup or result in a loss of SemGroup employees.

In connection with the pending merger, it is possible that some customers, suppliers and other persons with whom SemGroup has a business relationship may delay or defer certain business decisions or might decide to seek to terminate, change or renegotiate their relationship with SemGroup as a result of the merger, which could negatively impact revenues, earnings and cash flows of SemGroup, as well as the market price of shares of SemGroup common stock, regardless of whether the merger is completed. Similarly, current and prospective employees of SemGroup may experience uncertainty about their future roles with Energy Transfer and SemGroup following completion of the merger, which may materially adversely affect the ability of SemGroup to attract and retain key employees.

Failure to complete the merger could negatively affect the stock price of SemGroup and its future businesses and financial results.

If the merger is not completed, the ongoing business of SemGroup may be adversely affected and SemGroup will be subject to several risks and consequences, including the following:

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In addition, if the merger is not completed, SemGroup may experience negative reactions from the financial markets and from its customers and employees. SemGroup also could be subject to litigation related to any failure to complete the merger or to enforcement proceedings commenced against SemGroup to attempt to force it to perform its obligations under the merger agreement.

Pending litigation against Energy Transfer and SemGroup could result in an injunction preventing completion of the merger, the payment of damages in the event the merger is completed and/or may adversely affect the combined company’s business, financial condition or results of operations following the merger.

In connection with the merger, purported stockholders of SemGroup have filed a stockholder class action lawsuit against Energy Transfer, SemGroup, Merger Sub and the SemGroup board of directors in the United States District Court for the District of Delaware. Among other remedies, the plaintiffs seek to enjoin the merger. If a final settlement is not reached, or if a dismissal is not obtained, these lawsuits could prevent or delay completion of the merger and result in substantial costs to Energy Transfer and SemGroup, including any costs associated with the indemnification of directors. Additional lawsuits may be filed against Energy Transfer and/or SemGroup related to the merger. Any litigation relating to the merger could distract Energy Transfer or SemGroup from pursuing the consummation of the merger and other potentially beneficial business opportunities. Further, the defense or settlement of any lawsuit or claim that remains unresolved at the time the merger is completed may adversely affect the combined company’s business, financial condition or results of operations. See the section titled “Proposal 1: The Merger – Litigation Related to the Merger.”

Tax Risks Related to the Merger

Your exchange of SemGroup common stock for ET common units could be fully taxable in certain circumstances.

In general, a U.S. holder of SemGroup common stock should recognize gain or loss only to the extent that such U.S. holder is treated as exchanging a portion of such U.S. holder’s SemGroup common stock for cash pursuant to the merger. However, the exchange of SemGroup common stock for ET common units pursuant to the merger would be fully taxable for U.S. federal income tax purposes if, immediately after the merger Energy Transfer were characterized, for U.S. federal income tax purposes, as an “investment company.” Energy Transfer is seeking a private letter ruling from the IRS to the effect that, for U.S. federal income tax purposes, Energy Transfer will not be characterized as an “investment company.” For a more detailed discussion, please see “Material U.S. Federal Income Tax Consequences of the Merger.”

Tax Risks Related to Owning ET Common Units Following the Merger

Energy Transfer may engage in transactions that cause you to be subject to taxation in a manner different from other holders of ET common units.

Following the merger, in the event Energy Transfer divests itself of any SemGroup common stock, all or a portion of any gain or loss recognized as a result of a divestiture of such stock may be required to be allocated to former SemGroup stockholders. In addition, a former SemGroup stockholder may also be required to recognize its share of “built-in gain” upon certain distributions by Energy Transfer to that unitholder of other Energy Transfer property (other than money) within seven years following the merger. No special distributions will be made to the former SemGroup stockholders with respect to any tax liability for such transactions. Please see “Material U.S. Federal Income Tax Consequences of ET Common Unit Ownership – Tax Consequences of Unit Ownership – Allocation of Income, Gain, Loss and Deduction.”

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Other Risks

Following the merger, in addition to the risks described above, holders of ET common units, for U.S. federal income tax purposes, will continue to be subject to the risks that holders of ET common units are currently subject to, which are described in Energy Transfer’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018, as updated by any subsequent Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, all of which are filed with the SEC and incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information” for the location of information incorporated by reference in this proxy statement/prospectus.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This document includes “forward-looking statements” about Energy Transfer and SemGroup that are subject to risks and uncertainties. All statements other than statements of historical fact included in this document are forward-looking statements. Statements using words such as “anticipate,” “believe,” “intend,” “project,” “plan,” “expect,” “continue,” “estimate,” “goal,” “forecast,” “may,” “will,” or similar expressions help identify forward-looking statements.

Except for their respective obligations to disclose material information under U.S. federal securities laws, neither Energy Transfer nor SemGroup undertakes any obligation to release publicly any revisions to any forward-looking statements, to report events or circumstances after the date of this document, or to report the occurrence of unanticipated events.

Forward-looking statements involve a number of risks and uncertainties, and actual results or events may differ materially from those projected or implied in those statements. Important factors that could cause such differences include, but are not limited to:

In addition, the acquisition of SemGroup by Energy Transfer is subject to the satisfaction of certain conditions and the absence of events that could give rise to the termination of the merger agreement, the possibility that the merger does not close, risks that the proposed acquisition disrupts current plans and operations and business relationships or poses difficulties in attracting or retaining employees, the possibility that the costs or difficulties related to the integration of the two companies will be greater than expected and the possibility that the anticipated benefits from the merger cannot or will not be fully realized.

All written and oral forward-looking statements attributable to Energy Transfer or SemGroup or persons acting on behalf of Energy Transfer or SemGroup are expressly qualified in their entirety by such factors. For additional information with respect to these factors, please see the section entitled “Where You Can Find More Information.”

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INFORMATION ABOUT THE COMPANIES

Energy Transfer LP

Energy Transfer is a Delaware limited partnership with common units traded on the NYSE under the symbol “ET.” Energy Transfer owns and operates one of the largest and most diversified portfolios of energy assets in the United States, with a strategic footprint in all of the major domestic production basins. Energy Transfer, through its ownership of Energy Transfer Operating, L.P., also owns Lake Charles LNG Company, as well as limited partner interests and the general partner interests in Sunoco LP and USA Compression Partners, LP, both of which are publicly traded master limited partnerships engaged in diversified energy-related services.

The activities in which Energy Transfer is engaged, all of which are in the United States, are as follows:

Energy Transfer’s executive offices are located at 8111 Westchester Drive, Suite 600, Dallas, Texas 75225, and its telephone number is (214) 981-0700.

SemGroup Corporation

SemGroup is a Delaware corporation with common stock traded on the NYSE under the symbol “SEMG.” SemGroup moves energy across North America through a network of pipelines, processing plants, refinery-connected storage facilities and deep-water marine terminals with import and export capabilities. SemGroup serves as a versatile connection between upstream oil and gas producers and downstream refiners and end users. Key areas of operation and growth include western Canada, the Mid-Continent and the Gulf Coast. SemGroup is committed to safe, environmentally sound operations.

SemGroup’s key operations include:

SemGroup’s operations are conducted directly and indirectly through its primary operating segments: U.S. Liquids, U.S. Gas and Canada. U.S. Liquids includes SemGroup’s U.S. crude oil operations, including the Houston Fuel Oil Terminal Company. U.S. Gas contains the SemGas segment. Canada includes the operations of the SemCAMS segment.

SemGroup’s principal executive offices are located at Two Warren Place, 6120 South Yale Avenue, Suite 1500, Tulsa, Oklahoma 74136, and its telephone number is (918) 524-8100.

Nautilus Merger Sub LLC

Merger Sub is a Delaware limited liability company and a wholly owned subsidiary of Energy Transfer. Merger Sub was formed on September 12, 2019 solely for the purpose of consummating the merger and has no operating assets. Merger Sub has not carried on any activities to date, except for activities incidental to its formation and activities undertaken in connection with the transactions contemplated by the merger agreement.

Merger Sub’s principal executive offices are located at 8111 Westchester Drive, Suite 600, Dallas, Texas 75225, and its telephone number is (214) 981-0700.

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SPECIAL MEETING OF SEMGROUP STOCKHOLDERS

This section contains information about the special meeting of SemGroup stockholders that has been called, among other reasons, to approve and adopt the merger agreement and the transactions contemplated thereby and to approve, on an advisory (non-binding) basis, specified compensation that may be received by SemGroup’s named executive officers in connection with the merger. This document is being furnished to SemGroup stockholders in connection with the solicitation of proxies by the SemGroup board of directors to be used at the special meeting. SemGroup is first mailing this document and enclosed proxy card on or about October 31, 2019.

Date, Time and Place of the Special Meeting

A special meeting of SemGroup stockholders will be held at Two Warren Place, 5th Floor, 6120 South Yale Avenue, Tulsa, Oklahoma 74136 on December 4, 2019, starting at 9:00 a.m., local time (unless it is adjourned or postponed to a later date).

Admission to the Special Meeting

All SemGroup stockholders are invited to attend the special meeting. Persons who are not SemGroup stockholders may attend only if invited by SemGroup. If you own shares in “street” or “nominee” name, you must bring proof of ownership (e.g., a current broker’s statement) in order to be admitted to the special meeting.

Purpose of the Special Meeting

Recommendation of the SemGroup Board of Directors

The SemGroup board of directors has unanimously determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are fair to, and in the best interests of, SemGroup and its stockholders, and recommends that the SemGroup stockholders vote to approve and adopt the merger agreement and the transactions contemplated thereby, including the merger. In addition, the SemGroup board of directors recommends that the SemGroup stockholders vote to approve, on an advisory (non-binding) basis, specified compensation that may be received by SemGroup’s named executive officers in connection with the merger and to approve any adjournment of the special meeting, if necessary, to solicit additional proxies in favor of the merger proposal.

SemGroup stockholders should carefully read this document in its entirety for more detailed information concerning the merger agreement and the transactions contemplated thereby. In particular, SemGroup stockholders are directed to the merger agreement, which is attached hereto as Annex A.

Record Date; Stockholders Entitled to Vote; Outstanding Shares Held

The SemGroup board of directors has designated the close of business on October 25, 2019 as the “record date” that will determine the stockholders who are entitled to receive notice of, and to vote at, the special meeting

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or at any adjournment or postponement of the special meeting. Only holders of record at the close of business on the record date are entitled to vote at the special meeting. At the close of business on the record date, there were (i) 79,606,089 shares of SemGroup common stock outstanding, held by approximately 2,239 holders of record and (ii) 350,000 shares of SemGroup preferred stock outstanding, held by approximately seven holders of record. Each holder of shares of SemGroup common stock is entitled to one vote per share of SemGroup common stock held. Each holder of shares of SemGroup preferred stock is entitled to a number of votes equal to the number of votes such holder would have had if all shares of SemGroup preferred stock held by such holder had been converted into shares of SemGroup common stock as of the record date. As of the record date, the outstanding shares of SemGroup preferred stock were convertible into an aggregate of 11,987,820 shares of SemGroup common stock and such amount represents an equal number of votes that may be cast at the special meeting in person or by proxy by holders of such stock. There are no other classes of SemGroup stock outstanding. Accordingly, the total number of shares entitled to vote at the special meeting, giving effect to the SemGroup preferred stock, on an as-converted basis, is 91,593,909.

Quorum

A “quorum” shall consist of the holders of record of a majority of the issued and outstanding shares of SemGroup common stock and shares of SemGroup preferred stock, on an as-converted basis, entitled to vote at the special meeting, present in person or by proxy. There must be a quorum for the special meeting to be held. If you submit a timely, properly executed proxy or voting instruction card, then you will be considered part of the quorum so long as your shares are voted on at least one item of business, other than a procedural motion.

Failure to Vote; Abstentions

The failure of any SemGroup stockholder to submit a vote (e.g., by not submitting a proxy or not voting in person) and any abstention by a SemGroup stockholder will have the same effect as a vote “AGAINST” the merger proposal. In addition, abstentions are counted as shares present and entitled to vote and will have the same effect as votes “AGAINST” the advisory compensation proposal and the adjournment proposal.

Broker Non-Votes

Under the rules that govern brokers who have record ownership of shares that they hold in street name for their clients who are the beneficial owners of the shares, brokers have the discretion to vote such shares on routine matters, but not on non-routine matters absent direction from the stockholder, including the merger proposal, the advisory compensation proposal and the adjournment proposal. Broker non-votes occur when shares held by a broker are not voted with respect to a proposal because (1) the broker has not received voting instructions from the beneficial owner, and (2) the broker lacks the authority to vote the shares at his or her discretion. Because approval of the merger proposal requires the affirmative vote of at least a majority of the outstanding shares of SemGroup common stock, and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon at the special meeting, a broker non-vote will have the same effect as a vote “AGAINST” approval of the merger proposal. Because approval of each of the advisory compensation proposal and the adjournment proposal requires the affirmative vote of a majority of the shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon and present in person or represented by proxy at the special meeting, a broker non-vote will have no effect on the approval of the advisory compensation proposal or the adjournment proposal.

Required Vote

The merger proposal must be approved and adopted by the affirmative vote of the holders of a majority of the outstanding shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon at the special meeting. Abstentions and broker non-votes will be the equivalent of a vote “AGAINST” the merger proposal.

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Approval of the advisory vote on the advisory compensation proposal requires the affirmative vote of the holders of a majority of the shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon and present in person or represented by proxy at the special meeting. Abstentions will be the equivalent of a vote “AGAINST” the advisory compensation proposal. Broker non-votes will have no effect on the adoption of the advisory compensation proposal.

Approval of the adjournment proposal the affirmative vote of the holders of a majority of the shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon and present in person or represented by proxy at the special meeting. Abstentions will be the equivalent of a vote “AGAINST” a proposal to adjourn the special meeting. Broker non-votes will have no effect on the adoption of the adjournment proposal.

Shares Beneficially Owned by Directors and Executive Officers

The members of the SemGroup board of directors and executive officers of SemGroup beneficially owned an aggregate of 846,232 shares of SemGroup common stock as of October 25, 2019. These shares represent in total approximately 1% of the total voting power of SemGroup’s voting securities on an as-converted basis.

Proxies

You may vote in person by ballot at the special meeting or by submitting a proxy. Please submit your proxy even if you plan to attend the special meeting. If you attend the special meeting, you may vote by ballot, thereby canceling any proxy previously given.

Voting instructions are included on your proxy card. If you properly give your proxy and submit it to SemGroup in time for it to be voted, one of the individuals named as your proxy will vote your shares as you have directed. You may vote for or against the proposals or abstain from voting.

Shares Held in Street Name

If you hold shares of SemGroup common stock in the name of a bank, broker or other nominee, you should follow the instructions provided by your bank, broker or nominee when voting your shares of SemGroup common stock or when granting or revoking a proxy.

Absent specific instructions from you, your broker is not empowered to vote your shares of SemGroup common stock at the special meeting. The shares of SemGroup common stock not voted because brokers lack power to vote them without instructions are also known as “broker non-votes.”

How to Submit Your Proxy

By Mail: To submit your proxy by mail, simply mark your proxy, date and sign it, and if you are a record holder of shares of SemGroup common stock or SemGroup preferred stock, return it in the postage-paid envelope provided. If the envelope is missing, please address your completed proxy card to the address on your proxy card. If you are a beneficial owner, please refer to your instruction card or the information provided to you by your bank, broker, custodian or record holder.

By Telephone: If you are a SemGroup stockholder of record, you can submit your proxy by telephone by calling the toll-free telephone number on your proxy card. Telephone voting is available 24 hours a day and will be accessible until 12:00 a.m. Eastern time on December 3, 2019. Easy-to-follow voice prompts allow you to submit your proxy and confirm that your instructions have been properly recorded. If you are a beneficial owner, please refer to your instruction card or the information provided by your bank, broker, custodian or record holder for information on whether telephone voting is offered. If you submit your proxy by telephone you do not need to return your proxy card. If you are located outside the United States, Canada and Puerto Rico, please read your proxy card or other materials for additional instructions.

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By Internet: You can also choose to submit your proxy on the internet. If you are a SemGroup stockholder of record, the website for internet voting is on your proxy card. Internet voting is available 24 hours a day and will be accessible until 12:00 a.m. Eastern time on December 3, 2019. If you are a beneficial owner, please refer to your instruction card or the information provided by your bank, broker, custodian or record holder for information on whether internet voting is offered. As with telephone voting, you will be given the opportunity to confirm that your instructions have been properly recorded. If you submit your proxy on the internet, you do not need to return your proxy card.

In Person: If you are a SemGroup stockholder of record, you may vote by ballot at the special meeting or send a representative with an acceptable proxy that has been signed and dated. If your shares of SemGroup common stock or SemGroup preferred stock are held in the name of a bank, broker, custodian or other nominee, you must obtain a proxy, executed in your favor, from the holder of record, to be able to vote at the special meeting.

Revoking Your Proxy

If you submit a completed proxy card with instructions on how to vote your shares of SemGroup common stock or SemGroup preferred stock and then wish to revoke your instructions, you should submit a notice of revocation to the Secretary of SemGroup as soon as possible. You may revoke your proxy by internet, telephone or mail at any time before it is voted by:

Adjournments and Postponements

Any adjournment of the special meeting, if necessary, to solicit additional proxies in favor of adjournment proposal requires the affirmative vote of the holders of a majority of the shares of SemGroup common stock and SemGroup preferred stock, on an as-converted basis, voting as a single class, entitled to vote thereon and present in person or represented by proxy at the special meeting. Unless the SemGroup board of directors fixes a new record date for the adjourned special meeting, or law otherwise requires, no notice of the adjourned special meeting will be given so long as the time and place to which the special meeting is adjourned are announced at the special meeting adjourning and, at the adjourned special meeting only such business is transacted as might have been transacted at the original special meeting.

In addition, at any time prior to convening the special meeting, the special meeting may be postponed without the approval of SemGroup stockholders. If postponed, SemGroup will publicly announce the new meeting date. Similar to adjournments, any postponement of the special meeting for the purpose of soliciting additional proxies will allow SemGroup stockholders who have already sent in their proxies to revoke them at any time prior to their use.

Inspector of Election

The SemGroup board of directors has appointed a representative of Computershare Trust Company, N.A. to act as the inspector of election at the special meeting.

Proxy Solicitation

Energy Transfer and SemGroup will each bear their own costs related to the merger and the retention of any information agent or other service provider in connection with the merger, except for the expenses incurred in

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connection with the filing, printing and mailing of this document, which will be shared equally. This proxy solicitation is being made by SemGroup on behalf of the SemGroup board of directors. SemGroup has hired D.F. King & Co., Inc. to assist in the solicitation of proxies. In addition to this mailing, proxies may be solicited by directors, officers or employees of SemGroup or its affiliates in person or by telephone or electronic transmission. None of the directors, officers or employees will be directly compensated for such services.

Householding of Special Meeting Materials

Unless SemGroup has received contrary instructions, SemGroup may send a single copy of this proxy statement/prospectus to any household at which two or more stockholders reside if SemGroup believes the stockholders are members of the same family. Each stockholder in the household will continue to receive a separate proxy card. This process, known as “householding,” reduces the volume of duplicate information received at your household and helps to reduce SemGroup’s expenses.

Other Business

The SemGroup board of directors is not currently aware of any business to be acted upon at the special meeting other than the matters described in this document. If, however, other matters are properly brought before the special meeting, the persons appointed as proxies will have discretion to vote or act on those matters as in their judgment is in the best interest of SemGroup and its stockholders.

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PROPOSAL 1: THE MERGER

Effects of the Merger

Upon satisfaction or waiver of the conditions to closing in the merger agreement, on the closing date, Merger Sub, a wholly owned subsidiary of Energy Transfer formed for the purpose of effecting the merger, will merge with and into SemGroup, and SemGroup will be the surviving company in the merger and become a direct wholly owned subsidiary of Energy Transfer. At the effective time, each share of SemGroup common stock issued and outstanding immediately prior to the effective time (other than shares (w) held by SemGroup in treasury, (x) held directly by Energy Transfer or Merger Sub, (y) held by subsidiaries of the parties or (z) held by any holder who properly exercises and perfects appraisal rights in respect of such shares) will be cancelled and converted into the right to receive (i) $6.80 in cash, without interest, and (ii) 0.7275 of an ET common unit (collectively, the “merger consideration”). In addition, all shares of SemGroup preferred stock outstanding as of immediately prior to the effective time will be redeemed by SemGroup at a cash purchase price per share equal to 101% of the liquidation preference. SemGroup will take all actions as may be necessary so that at the effective time, each outstanding award of restricted share units, restricted stock awards and performance share units of SemGroup will be treated as described in “The Merger Agreement – SemGroup Employee Equity-Based Awards.”

Background of the Merger

The terms of the merger are the result of arm’s length negotiations between Energy Transfer and SemGroup. The following is a summary of the events leading up to the signing of the merger agreement and the key meetings, negotiations, discussions and actions by and between Energy Transfer and SemGroup and their respective advisors that preceded the public announcement of the acquisition.

As part of SemGroup’s ongoing strategic planning process, the SemGroup board of directors, together with SemGroup’s executive management team, regularly reviews and assesses SemGroup’s long-term strategic plans and goals, opportunities, overall industry trends, the competitive environment in which SemGroup operates and SemGroup’s short- and long-term performance. As part of these reviews, the SemGroup board of directors, with the assistance of SemGroup’s advisors, considered whether various strategic actions, including business combination transactions and joint venture opportunities, would be in the best interests of SemGroup and would enhance value for SemGroup’s stockholders. Arising out of such a strategic evaluation and in conjunction with the SemGroup board of directors’ ongoing analysis, from March 2019 through the announcement of the transaction, the SemGroup board of directors evaluated the merits of a joint venture opportunity that would involve the contribution by SemGroup of most of its crude oil related assets, including the Houston Fuel Oil Terminal Company assets, in exchange for ownership in a newly formed joint venture and cash (the “proposed joint venture”) with Company A, a large North American oil and gas infrastructure company. As part of such analysis, the SemGroup board of directors also considered whether the pursuit of the transaction might preclude future flexibility or might enhance or detract from the ability to pursue future consolidation or change of control transactions, including the allocation of the SemGroup executive management team’s time and resources to such a transaction in addition to pursuing and executing SemGroup’s strategic growth initiatives and maintaining operational excellence.

On July 12, 2019, representatives of SemGroup received an unsolicited acquisition proposal from Energy Transfer for an aggregate value of $15.56 per share of SemGroup common stock, which represented a 25.0% premium to SemGroup’s then-current trading price. Representatives of SemGroup posted the acquisition proposal to the SemGroup board of directors and the SemGroup board of directors determined to discuss the proposal early the next week.

On July 15, 2019, the SemGroup board of directors convened via telephone for an update meeting including representatives of Jefferies to discuss the proposed joint venture as well as initial impressions of the Energy

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Transfer proposal. No financial analysis of the Energy Transfer proposal was presented at that time and Energy Transfer had not yet given an indication of the relative mix of cash and equity consideration at such time. The SemGroup board of directors instructed Jefferies to continue its analysis. Jefferies had previously been retained by SemGroup management and the SemGroup board of directors on January 16, 2019 to act as a financial advisor in connection with the evaluation of various strategic transactions that may arise from time to time, including preliminary discussions regarding a business combination with Company B, an oil and gas gathering and processing company with operations in the United States, which were terminated soon thereafter. The SemGroup board of directors instructed Mr. Carlin Conner, President and Chief Executive Officer of SemGroup, to respond to Mr. Kelcy Warren, Chief Executive Officer and Chairman of the ET board of directors, in order to investigate the Energy Transfer acquisition proposal.

On July 16, 2019, Messrs. Conner and Warren spoke via telephone regarding the acquisition proposal and agreed to meet in Dallas, Texas in August.

On July 17, 2019, the SemGroup board of directors convened again via telephone for an update to discuss Energy Transfer’s proposal as well as certain aspects of the proposed joint venture with Company A.

On August 1, 2019, Mr. Conner met with Mr. Warren in Dallas, Texas to discuss the potential acquisition of SemGroup by Energy Transfer and potential commercial projects between the two companies. Messrs. Conner and Warren, together with Mr. Thomas E. Long who later joined the meeting, discussed several economic and operational factors that may influence Energy Transfer’s and SemGroup’s view of a potential acquisition of SemGroup by Energy Transfer. Messrs. Conner and Warren agreed to discuss further if, after Mr. Conner discussed with the SemGroup board of directors, the SemGroup board of directors determined to further investigate a business combination with Energy Transfer.

On August 14, 2019, the SemGroup board of directors convened again, together with representatives from SemGroup’s executive management team, Jefferies, and Kirkland and Ellis LLP (“Kirkland”), via telephone for a special meeting to discuss Energy Transfer’s proposal as well as the status of the proposed joint venture transaction with Company A. Kirkland had previously been retained by SemGroup management and the SemGroup board of directors in January 2019 to assist in matters relating to a strategic transaction involving Company B. At the meeting, the SemGroup board of directors discussed, among other things, continuing to pursue SemGroup’s corporate strategy, including the proposed joint venture with Company A, in tandem with the evaluation of Energy Transfer’s proposal. At the request of the SemGroup board of directors, Jefferies presented its financial analysis of the Energy Transfer proposal based on publicly-available information. The SemGroup board of directors authorized Mr. Conner to further discuss the proposed transaction with Mr. Warren.

On August 19, 2019, Mr. Conner and Mr. Warren spoke via telephone to discuss, among other things, the economic terms of Energy Transfer’s July 12 proposal.

On August 20, 2019, Company A revised the terms of its proposal by reducing the implied value of SemGroup’s assets and modified the structure of the proposed joint venture. Representatives of SemGroup reported Company A’s revised terms of the proposed joint venture to the SemGroup board of directors that same day. Mr. Thomas R. McDaniel instructed representatives of SemGroup’s executive management team and Jefferies to prepare a revised analysis of the proposed joint venture transaction for the SemGroup board of directors to review at a special meeting of the SemGroup board of directors later in August.

That same week, on August 22, 2019, Company C, a private equity firm, reported that Company C had met with a stockholder of SemGroup and, following such discussions, proposed to Mr. Conner that Company C would be willing to acquire SemGroup in a take-private transaction for an indicative value of $16.50 per share of SemGroup common stock, subject to confirmation from Company C’s investment committee. That same day, Mr. Conner reported Company C’s proposal to the SemGroup board of directors. The SemGroup board of directors determined to further evaluate the proposals from Energy Transfer and, if and when received, Company C together with the revised terms of the proposed joint venture with Company A, and other strategic options.

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On August 23, 2019, Energy Transfer submitted a revised acquisition proposal that improved Energy Transfer’s initial, July 12, 2019 proposal. Energy Transfer proposed that it would acquire SemGroup for $17.00 per share of SemGroup common stock, which represented a 78.9% premium to SemGroup’s then-current trading price, and that Energy Transfer and SemGroup would enter into a confidentiality agreement to commence sharing certain commercial and legal information. That same day, SemGroup and Energy Transfer executed a confidentiality agreement and began to share certain confidential commercial and legal information.

On August 25, 2019, SemGroup executed a confidentiality agreement with Company C. SemGroup shared certain confidential information with Company C and at the request of the SemGroup board of directors, representatives of Jefferies requested that Company C confirm its oral proposal from August 22.

Each confidentiality and standstill agreement entered into by SemGroup that is described in this section contained customary “standstill” and “don’t ask, don’t waive” provisions, subject to a customary “fall away” provision, which provided that the restrictions in the “standstill” would terminate if, among other things, SemGroup entered into a business combination agreement with a person or group that would result in SemGroup’s common equity holders owning less than 50% of the common or equivalent equity of the surviving entity resulting from such business combination. These standstill provisions also did not prohibit the counterparty from making a non-public proposal to SemGroup.

On August 26, 2019, SemGroup received a non-binding written acquisition proposal from Energy Transfer that clarified certain transaction details including (i) that the consideration would consist of 60% equity and 40% cash, with the equity component reflecting an exchange ratio of 0.7275 Energy Transfer common units per share of SemGroup common stock, and (ii) the assumed redemption of SemGroup preferred stock at 101% premium of the liquidation preference.

On August 27, 2019, at a special meeting, the SemGroup board of directors, together with representatives of the SemGroup executive management team, Kirkland and Jefferies, evaluated Energy Transfer’s revised acquisition proposal. The SemGroup board of directors discussed its view of the strategic alternatives available to SemGroup at the time, including soliciting additional offers, remaining a standalone company, and the timing of evaluating and responding to proposals. Thereafter, the SemGroup board of directors determined that it would not agree to exclusivity with any counterparty at such time. Further, the SemGroup board of directors instructed representatives of Jefferies to proceed with a market check process in order to seek additional indications of value for SemGroup from other counterparties. The SemGroup board of directors also discussed the appropriate framework for evaluating potential offers from different counterparties, including strategic buyers and private equity firms, as well as the potential value achievable from entering into the proposed joint venture transaction with Company A. That same day, representatives of Jefferies contacted a group of strategic and financial counterparties to gauge interest in a strategic transaction, including Company D, a publicly-traded midstream company with operations in the United States; Company E, a publicly-traded midstream company with operations in the United States and Canada; Company F, a private equity firm with a diverse investment profile; Company G, a private equity firm with an energy-industry investment focus; and Company H, a private equity fund with an infrastructure investment focus. That same day, Energy Transfer sent SemGroup a proposed exclusivity agreement.

On August 28, 2019, an energy industry focused private equity firm, Company I, requested the opportunity to submit a proposal with respect to a take-private, or similar, acquisition of SemGroup. Representatives of Jefferies encouraged Company I to do so, though no proposal was ultimately submitted. That same day and acting at the instruction of the SemGroup board of directors, representatives of Jefferies informed representatives of Energy Transfer that SemGroup would not agree to negotiate on an exclusive basis at this time and the parties agreed to a meeting on September 3, 2019 in Dallas, Texas.

On August 29, 2019, Company G submitted a proposal to acquire SemGroup in a take-private transaction for $15.00 per share of SemGroup common stock, which represented a 73.0% premium to SemGroup’s then-

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current trading price and proposed the redemption of SemGroup preferred stock at 101% of the liquidation preference. Company G also proposed that SemGroup and Company G enter into exclusive negotiations for 60 days. That same day, Company H indicated that, after finishing its initial review of publicly-available information regarding SemGroup, it would not submit a proposal.

On August 30, 2019, Company C informed representatives of Jefferies that Company C did not receive approval from its investment committee in order to affirm its August 22 oral proposal.

On September 3, 2019, representatives of SemGroup, including members of the SemGroup executive management team, Jefferies, Kirkland and Mr. McDaniel, met with representatives of Energy Transfer, including members of Energy Transfer’s executive management team, BofA Securities, Inc. (“BofA Merrill Lynch”), financial advisor to Energy Transfer, and Latham and Watkins LLP (“Latham”), legal counsel to Energy Transfer, in Dallas, Texas to discuss commercial and financial due diligence matters. Materials were prepared by each respective company and their advisors in order to facilitate the due diligence discussions.

On September 4, 2019, Latham sent a draft of the merger agreement to Kirkland. The draft contemplated, among other things: (i) a reverse triangular merger that would be partially tax-free to SemGroup’s stockholders; (ii) non-solicitation provisions that would allow the SemGroup board of directors, under certain circumstances, to change its recommendation in the event of a superior proposal or intervening event and to terminate the merger agreement to accept a superior proposal; and (iii) an unspecified breakup fee payable by SemGroup in the event the agreement was terminated by SemGroup to accept a superior proposal, or by Energy Transfer following a change in recommendation, or by SemGroup in connection with the entry into an alternative proposal. Members of SemGroup management and representatives of Kirkland discussed and evaluated the terms of the draft merger agreement over the following days. That same day, Energy Transfer provided SemGroup with a due diligence request list.

On September 5, 2019, Company D submitted to Jefferies a non-binding proposal regarding the acquisition of all of the outstanding SemGroup common stock in exchange for Company D stock valued at approximately $12.00 per share, which represented a 37.5% premium to SemGroup’s then-current trading price. Company D’s proposal did not specify treatment of the SemGroup preferred stock. Thereafter, there were no further substantive communications with Company D regarding a potential strategic transaction between SemGroup and Company D.

That same day, SemGroup populated a virtual data room (“VDR”) as well as a physical data room for due diligence purposes. Shortly thereafter, SemGroup opened access to its VDR to Energy Transfer and its legal and financial advisors.

On September 6, 2019, SemGroup received a proposal from Company E offering to acquire SemGroup for an indicative value of $13.50 per share of SemGroup common stock, which represented a 53.1% premium to SemGroup’s then-current trading price but did not indicate whether such consideration would be cash or stock at such time nor the treatment of SemGroup preferred stock.

That same day, SemGroup received a proposal from Company F offering to acquire SemGroup in a take-private transaction (i) for consideration in the range of $13.50 to $15.00 per share of SemGroup common stock, which represented a 53 to 70% premium to SemGroup’s then-current trading price, (ii) that contemplated the redemption of SemGroup preferred stock at 101% of the liquidation preference, and (iii) proposed that SemGroup and Company F enter into exclusive negotiations through October 15, 2019 in furtherance thereof.

That same day, representatives from each of Energy Transfer’s and SemGroup’s executive management teams, Jefferies, Kirkland, BofA Merrill Lynch, and Latham convened via teleconference to participate in due diligence sessions regarding, among other things, human resources and environmental, health and safety matters. The next day, the same group convened via telephone to discuss tax due diligence matters.

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Throughout the market check process, representatives of SemGroup and Jefferies posted to the SemGroup board of directors each of the proposals, and declinations to submit any such proposal, to the SemGroup board of directors in substantially real time. The SemGroup board of directors agreed to refrain from an in-depth discussion on any such matters until the SemGroup board of directors convened to evaluate the preliminary results of the market check process.

On September 8, 2019, the SemGroup board of directors held a special meeting and invited representatives from each of SemGroup’s executive management team, Jefferies, and Kirkland to attend. At this meeting, representatives of Jefferies presented, and the SemGroup board of directors reviewed, the preliminary outcome of the market check process and the financial analyses related to the proposals received to date. The SemGroup board of directors decided to (i) pursue negotiation of a definitive acquisition agreement with Energy Transfer on a non-exclusive basis and (ii) provide Company A with the opportunity to make a proposal to acquire SemGroup for additional value or to improve the terms of the proposed joint venture transaction. The SemGroup board of directors authorized Jefferies and Kirkland to continue to hold preliminary meetings and share information under confidentiality and standstill agreements with these and other potential parties to a strategic combination. In addition, the SemGroup board of directors asked to be kept informed of any additional approaches by potential strategic counterparties on a substantially concurrent basis. That same day, representatives of Jefferies contacted Company A to advise per the SemGroup board of directors’ instruction. Later that same day, representatives from each of Energy Transfer’s and SemGroup’s executive management teams, Jefferies, Kirkland, BofA Merrill Lynch, and Latham convened via teleconference to participate in a legal due diligence session.

On September 9, 2019, a large, publicly-traded infrastructure company, Company J, requested from representatives of Jefferies the opportunity to submit a proposal with respect to an acquisition transaction of SemGroup. The representatives of Jefferies encouraged the representatives of Company J to do so. That same day, Messrs. McDaniel and Warren discussed on the phone Energy Transfer’s strategic rationale regarding integration of the SemGroup assets into Energy Transfer’s business together with Energy Transfer’s succession planning strategy.

On September 10, 2019, SemGroup executed a confidentiality agreement with Company E under substantially similar terms as the other confidentiality agreements except that the standstill provision also obligated SemGroup to refrain from solicitation activities in respect of Company E securities. That same day, representatives from each of Energy Transfer’s and SemGroup’s executive management teams, Jefferies, Kirkland, BofA Merrill Lynch, and Latham convened via teleconference to discuss additional commercial due diligence matters. After such discussions, representatives of Energy Transfer confirmed its acquisition proposal of $6.80 in cash and 0.7275 of an ET common unit per share of SemGroup common stock, subject to satisfactory completion of its confirmatory due diligence efforts. Representatives of Jefferies contacted representatives of each of Company E, Company F and Company G and encouraged them to increase their respective offers.

That same evening, Kirkland returned a draft of the merger agreement to Latham reflecting, among other things, (i) broader operational discretion during the pendency of the acquisition transaction in accordance with SemGroup’s fiscal budget and capital expenditure plan, (ii) revisions to certain employee compensation matters, including that SemGroup’s performance share units would vest at target at closing, (iii) a “hell-or-high-water” standard in respect of clearance under United States anti-competition laws, (iv) covenants in respect of Energy Transfer’s obligation to maintain an office in the Tulsa, Oklahoma metropolitan area for two years after closing and to maintain SemGroup’s charitable giving efforts, and (v) a proposed breakup fee equal to 2% of the equity value of SemGroup.

On September 11, 2019 and in response to Jefferies’ encouragement to revise the terms of the proposed joint venture, Company A proposed a transaction that would involve the contribution by SemGroup of most of its crude oil related assets, including the Houston Fuel Oil Terminal Company assets, in exchange for 50% ownership in a newly formed joint venture and cash. These terms reflected a lower ownership percentage and less cash than had been previously proposed by Company A. The SemGroup board of directors received the revised proposed joint venture terms that same day and, in the interest of comparing each potential counterparty’s

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best and final proposals, the SemGroup board of directors requested that representatives of Jefferies solicit additional merger consideration from Energy Transfer. On that same day, representatives of Jefferies conducted a financial due diligence session with representatives of Energy Transfer. On September 12, 2019, SemGroup executed a confidentiality agreement with each of Company F and Company G. That same day, Company J communicated to representatives of Jefferies that it declined to submit a proposal with respect to the acquisition of SemGroup, and Company E increased its proposed valuation to $14.25 per share of SemGroup common stock, which represented a 46.2% premium to SemGroup’s then-current trading price. That same day, representatives of Jefferies contacted representatives of Energy Transfer to negotiate for additional merger consideration. Energy Transfer declined to increase its offer of September 10th but reaffirmed its acquisition proposal of $6.80 in cash and 0.7275 an ET common unit per share of SemGroup common stock.

On September 12, 2019, Latham returned a draft of the merger agreement to Kirkland. The draft reflected, among other things, a breakup fee equal to 6% of the equity value of SemGroup, certain carve-outs and exclusions to the “hell-or-high-water” provision and reserved comment in respect of certain employee compensation matters pending additional information regarding the treatment thereof.

On September 13, 2019, in discussions between representatives of Jefferies and the applicable company, Company F indicated that, subject to incremental due diligence, it would be positioned to offer consideration to SemGroup’s stockholders at the high end of its September 6 proposal, while Company G indicated that it would not improve the terms of its August 29 proposal.

Throughout the balance of the market check process, representatives of Jefferies and SemGroup’s executive management team informed the SemGroup board of directors of the status of discussions. At no point prior to announcement of the proposed acquisition transaction with Energy Transfer did representatives of Jefferies disclose to a potential counterparty that the market check process had completed or otherwise preclude an increased proposal. As in the preliminary stages of the market check process, the SemGroup board of directors refrained from making decisions until the SemGroup board of directors had the benefit of the full results of the market check process, and the legal and financial analysis thereof, and any revisions to the terms of the proposed joint venture with Company A.

On September 13, 2019, the SemGroup board of directors convened telephonically to discuss the status of the market check process as well as the definitive documentation with Energy Transfer. Representatives of Jefferies (i) summarized that the market check process was unable to generate a higher valuation and that Energy Transfer’s offer, as delineated on September 10, 2019, remained the proposal that would generate the highest value to stockholders, (ii) summarized that SemGroup received indications of interest from Company D for $12.00 per share, Company E for $14.25 per share, Company F for $13.50 to $15.00 per share, Company G for $15.00 per share, and Energy Transfer for an aggregate value of $17.00 per share, and (iii) disclosed de minimis conflicts of both Jefferies and members of the deal team, which the SemGroup board of directors determined to be immaterial both individually and in the aggregate. Representatives of Jefferies discussed various aspects of the potential transaction, including, without limitation, (w) a situation update and a summary of key transaction terms proposed by each potential counterparty that submitted a proposal, (x) an overview and sensitivity analysis of valuation assumptions in respect of Energy Transfer’s proposal, (y) an overview of the valuation analyses of Energy Transfer and SemGroup, followed by detail regarding public market trading multiples, discounted cash flow analyses, and (z) a comparison of broker research target price estimates for ET and SemGroup. The SemGroup board of directors discussed the merits of the transaction and the financial analyses provided by Jefferies, together with the value to SemGroup’s stockholder expected to be achieved if the transaction were consummated. At the request of Mr. McDaniel, Kirkland reiterated the SemGroup board of directors’ fiduciary duties in respect of its consideration of a strategic transaction of this nature and discussed the timing of the proposed acquisition transaction with Energy Transfer. Kirkland also summarized the status of negotiations with Energy Transfer with respect to the merger agreement, including, (a) a proposed private letter ruling regarding the partially tax-free nature of the transaction, (b) treatment of the SemGroup preferred stock in compliance with the terms of the certificate of designations governing the terms thereof, (c) SemGroup’s non-solicitation obligations, including the prohibition against SemGroup soliciting an acquisition proposal during the pendency

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of the merger, (d) the break-up fee, (e) the “hell-or-high-water” standard and burden of risk in respect of clearance under United States anti-competition laws, and (f) the negative operating covenants during the pendency of the merger, including in respect of employee retention matters and charitable giving commitments.

Throughout the day on September 14, 2019, Energy Transfer and SemGroup agreed on the remaining key terms with respect to the merger agreement, including the treatment of the SemGroup preferred stock, certain covenants in respect of the interim operating period, the “hell-or-high-water” provision, the value of the breakup fee and expense reimbursement. Representatives of each of Kirkland and Latham exchanged drafts of the merger agreement.

Later that evening, Latham provided to representatives of Kirkland and SemGroup, a draft support agreement to be executed by WP SemGroup, the beneficial holder of approximately 85.7% of the SemGroup preferred stock, whereby WP SemGroup would agree to, among other things, vote all of the shares in SemGroup that it owns as of the record date for the SemGroup stockholder meeting (i) in favor of the adoption of the merger agreement, (ii) against any alternative acquisition proposal, and (iii) against any action, agreement, transaction or proposal that is intended, would reasonably be expected or the result of which would reasonably be expected, to materially impede, interfere with, delay, postpone, discourage, frustrate the purposes of or adversely affect the merger or the other transactions contemplated by the merger agreement. In addition, the draft support agreement contemplated that WP SemGroup and SemGroup would amend the Certificate of Designations such that the preferred stockholders could elect to receive cash in an amount equal to 101% of the liquidation preference of the preferred stock in connection with the merger and that WP SemGroup would agree to make such an election.

On September 15, 2019, legal counsel to WP SemGroup returned a draft of the support agreement to Latham reflecting, among other things, revised covenants related to voting and transfer restrictions, and the parties’ termination rights with respect to the support agreement.

Also on September 15, 2019, the ET board of directors held a special meeting to approve the merger, the merger agreement and the related transactions. After discussion, the merger, the merger agreement and the related transactions were unanimously approved and adopted by the ET board of directors.

That same day, the SemGroup board of directors convened a special meeting to discuss the proposed acquisition transaction with Energy Transfer, including the proposed final terms of the merger agreement. Representatives of Kirkland made a presentation to the SemGroup board of directors with respect to various matters, including, without limitation, (i) the board’s fiduciary duties in connection with its consideration of the transaction, (ii) an overview of the key terms of the merger agreement, including the compensation committee’s determination in respect of employee matters, (iii) an overview of the non-solicitation provisions of the merger agreement, (iv) the proposed support agreement by WP SemGroup, majority holder of the SemGroup preferred stock, (v) an illustrative timeline for the transaction from signing to closing, assuming the SemGroup board of directors approved the acquisition transaction, (vi) an update of SemGroup’s legal due diligence efforts, and (vii) a summary of the resolutions to come before the board in connection with the proposed acquisition transaction. Jefferies then provided a fairness presentation and responded to questions from the SemGroup board of directors. Thereafter, Jefferies orally rendered its fairness opinion to the SemGroup board of directors that, as of September 15, 2019, and based upon and subject to the assumptions made and limitations to be set forth in the opinion, the merger consideration to be received by the holders of SemGroup common stock (other than SemGroup and its affiliates) pursuant to the merger agreement is fair, from a financial point of view. Jefferies subsequently confirmed its fairness opinion in writing. After discussion, the SemGroup board of directors unanimously (i) determined that the merger agreement and transactions contemplated thereby, were advisable and in the best interests of SemGroup and its stockholders, (ii) approved the execution and delivery of the merger agreement, the performance by SemGroup of its covenants and agreements contained therein and the consummation of the transactions contemplated by the merger agreement, (iii) directed that the merger agreement be submitted to SemGroup stockholders at a special meeting of stockholders for its adoption, (iv) resolved to recommend that SemGroup stockholders approve the merger agreement and transactions contemplated thereby, including the merger, and (v) approved other matters related to the merger agreement.

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That evening, representatives of each of Kirkland and Latham finalized the merger agreement, disclosure schedules and ancillary documents, following which SemGroup and Energy Transfer executed and delivered the merger agreement that same day. Contemporaneously with the execution of the merger agreement, SemGroup, Energy Transfer and WP SemGroup executed the support agreement and SemGroup executed the Certificate of Designations.

Prior to the opening of U.S. stock markets on September  16, 2019, each of SemGroup and Energy Transfer issued a news release announcing the proposed acquisition transaction.

Recommendation of the SemGroup Board of Directors and Reasons for the Merger

On September 15, 2019, the SemGroup board of directors unanimously (a) determined that the merger agreement and the transactions contemplated thereby, including the merger, are fair to, and in the best interests of, SemGroup and its stockholders, (b) approved and declared advisable the merger agreement and the transactions contemplated thereby, including the merger, (c) approved the execution, delivery and performance of the merger agreement and the consummation of the transactions contemplated thereby, including the merger, (d) resolved to recommend adoption of the merger agreement by the SemGroup stockholders, and (e) directed that the merger agreement be submitted to the stockholders of SemGroup for its adoption. The SemGroup board of directors unanimously recommends that holders of SemGroup common stock vote “FOR” the SemGroup merger proposal and “FOR” the SemGroup compensation advisory proposal and “FOR” the SemGroup adjournment proposal.

In the course of reaching its determinations and recommendations, the SemGroup board of directors consulted with SemGroup’s senior management and its outside legal and financial advisors and considered several potentially positive factors that weighed in favor of the merger, including the following (not necessarily presented in order of relative importance):

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Opinion of Financial Advisor

Likelihood of Completion of the Transaction

Favorable Terms of the Merger Agreement

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The SemGroup board of directors also considered and balanced against the potentially positive factors a number of uncertainties, risks and other countervailing factors in its deliberations concerning the merger and the merger agreement, including the following (not necessarily presented in order of relative importance):

After taking into account the factors set forth above, as well as others, the SemGroup board of directors concluded that the risks, uncertainties, restrictions and potentially negative factors associated with the transaction were outweighed by the potential benefits of the transaction to SemGroup stockholders.

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The foregoing discussion of factors considered by SemGroup is not intended to be exhaustive but summarizes the material factors considered by the SemGroup board of directors. In light of the variety of factors considered in connection with their evaluation of the merger agreement and the transaction, SemGroup did not find it practicable to, and did not, quantify, rank or otherwise assign relative weights to the specific factors considered in reaching their determinations and recommendations. Moreover, each member of the SemGroup board of directors applied his or her own personal business judgment to the process and may have given different weight to different factors. The SemGroup board of directors based its recommendation on the totality of the information presented, including thorough discussions with, and questioning of, SemGroup’s senior management and the SemGroup board of directors’ outside legal and financial advisors.

In considering the recommendation of the SemGroup board of directors to approve the merger agreement, holders of SemGroup common stock should be aware that the executive officers and directors of SemGroup have certain interests in the transaction that may be different from, or in addition to, the interests of SemGroup stockholders generally. See the section entitled “—Interests of SemGroup’s Directors and Executive Officers in the Merger” beginning on page 54.

It should be noted that this explanation of the reasoning of the SemGroup board of directors and certain information presented in this section is forward-looking in nature and should be read in light of the factors set forth in “Cautionary Statement Regarding Forward-Looking Statements” beginning on page 27.

Opinion of SemGroup’s Financial Advisor

The SemGroup board of directors retained Jefferies as its financial advisor in connection with, among other things, the merger. At a meeting of the SemGroup board of directors on September 15, 2019, Jefferies rendered its opinion, to the effect that, as of that date and based upon and subject to the various assumptions made, procedures followed, matters considered and limitations on the scope of the review undertaken as set forth in its opinion, the merger consideration to be received by the Public Common Stock Holders pursuant to the merger agreement was fair, from a financial point of view, to the Public Common Stock Holders.

The full text of the written opinion of Jefferies, dated as of September 15, 2019, is attached hereto as Annex C. Jefferies’ opinion sets forth, among other things, the assumptions made, procedures followed, matters considered and limitations on the scope of the review undertaken by Jefferies in rendering its opinion. SemGroup encourages you to read Jefferies’ opinion carefully and in its entirety. Jefferies’ opinion was directed to the SemGroup board of directors (in its capacity as such) and addresses only the fairness from a financial point of view, of the merger consideration to be received by the Public Common Stock Holders pursuant to the merger agreement to such Public Common Stock Holders. It does not address the relative merits of the transactions contemplated by the merger agreement as compared to any alternative transaction or opportunity that might be available to SemGroup, nor does it address the underlying business decision by SemGroup to engage in the merger or the terms of the merger agreement or the documents referred to therein. Jefferies’ opinion does not constitute a recommendation as to how any securityholder should vote on the merger or any matter related thereto. The summary of the opinion of Jefferies set forth below is qualified in its entirety by reference to the full text of the opinion.

In arriving at its opinion, Jefferies, among other things:

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In Jefferies’ review and analysis and in rendering its opinion, Jefferies assumed and relied upon, but assumed no responsibility to independently investigate or verify, the accuracy and completeness of all financial and other information that was (i) supplied or otherwise made available by or on behalf of SemGroup or Energy Transfer, (ii) publicly available to Jefferies (including, without limitation, the information described above) or (iii) otherwise reviewed by Jefferies. Jefferies relied on assurances of the management of SemGroup and Energy Transfer and other representatives of SemGroup and Energy Transfer that they are not aware of any facts or circumstances that would make such information incomplete, inaccurate or misleading or of any relevant information that was omitted or undisclosed to Jefferies. In Jefferies’ review, Jefferies did not obtain an independent evaluation or appraisal of any of the assets or liabilities (contingent, derivative, off-balance sheet or otherwise), nor did Jefferies conduct a physical inspection of any of the properties or facilities, of SemGroup, Energy Transfer or any other entity, and Jefferies was not furnished with, and assumed no responsibility to obtain or conduct, any such evaluations, appraisals or physical inspections.

With respect to the financial forecasts and estimates provided to and examined by Jefferies, Jefferies’ opinion noted that projecting future results of any company is inherently subject to uncertainty. SemGroup informed Jefferies, however, and Jefferies assumed, that such financial forecasts and estimates relating to SemGroup that Jefferies was directed to use for purposes of its analyses and opinion were reasonably prepared on bases reflecting the best then-available estimates and good faith judgments of the management of SemGroup as to the future financial performance of SemGroup and the other matters covered thereby. With respect to the financial forecasts and estimates relating to Energy Transfer that the management of Energy Transfer provided to Jefferies and confirmed as appropriate for use in Jefferies’ analyses with respect to Energy Transfer, Jefferies was informed by Energy Transfer, and Jefferies assumed, that such financial forecasts and estimates are a reasonable basis upon which to evaluate Energy Transfer. Jefferies expressed no opinion as to the respective financial forecasts of SemGroup or Energy Transfer or the assumptions on which they are made.

Jefferies’ opinion was based on economic, monetary, regulatory, market and other conditions existing and which could be evaluated as of the date of its opinion. Jefferies expressly disclaimed any undertaking or obligation to advise any person of any change in any fact or matter affecting its opinion of which Jefferies becomes aware after the date of its opinion. Jefferies’ opinion noted that the credit, financial and stock markets, and the industry in which SemGroup and Energy Transfer operate, have experienced and may continue to experience volatility and Jefferies expressed no view or opinion as to any potential effects of such volatility on SemGroup, Energy Transfer or the merger.

Jefferies made no independent investigation of, and Jefferies expressed no view or opinion as to, any legal, regulatory, accounting or tax matters affecting SemGroup, Energy Transfer or the merger, and Jefferies assumed the correctness in all respects meaningful to its analyses and opinion, SemGroup, Energy Transfer or the merger

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of all legal, regulatory, accounting and tax advice given to SemGroup or the SemGroup board of directors, including, without limitation, advice as to the legal, regulatory, accounting and tax consequences of the terms of, and transactions contemplated by, the merger, the merger agreement and related documents. In addition, in preparing its opinion, Jefferies did not take into account any tax consequences of the transaction to any Public Common Stock Holder. Jefferies assumed that the final form of the merger agreement would be substantially similar to the last draft reviewed by Jefferies, and when signed by the parties thereto, would not differ from the last draft reviewed by Jefferies in any respect meaningful to its analyses or opinion. Jefferies also assumed that the merger and related transactions will be consummated in compliance with all applicable laws, documents and other requirements, in accordance with their terms without waiver, modification or amendment of any term, condition or agreement that would be meaningful in any respect to its analyses or opinion and that, in the course of obtaining the necessary regulatory or third-party approvals, consents and releases for the merger and related transactions, including with respect to any divestitures or other requirements, no delay, limitation, restriction or condition will be imposed that would have an adverse effect on SemGroup, Energy Transfer, the merger or the contemplated benefits of the merger.

Jefferies’ opinion noted that the opinion was for the use and benefit of the SemGroup board of directors (in its capacity as such) in its evaluation of the merger. Jefferies was not requested to, and Jefferies did not, participate in the structuring of the merger. Jefferies’ opinion did not address the relative merits of the transactions contemplated by the merger agreement as compared to any alternative transaction or opportunity that might be available to SemGroup, nor did it address the underlying business decision by SemGroup to engage in the merger, the terms of the merger agreement or the documents referred to therein, including the form or structure of the merger or any term, aspect or implication of any agreements, arrangements or understandings entered into in connection with, or contemplated by or resulting from, the merger or otherwise. Jefferies’ opinion does not constitute a recommendation as to how any securityholder or any other person should vote on or act with respect to the merger or any other matter. Jefferies’ opinion was limited to the fairness to Public Common Stock Holders, from a financial point of view, of the merger consideration, without regard to individual circumstances of specific holders of such units that may distinguish such holders or the securities of SemGroup held by such holders, and Jefferies was not asked to address, and its opinion did not address, the fairness, financial or otherwise, to, or any other consideration of, the holders of any class of securities, creditors or other constituencies of SemGroup, other than Public Common Stock Holders. Furthermore, Jefferies expressed no view or opinion as to the fairness, financial or otherwise, of the amount or nature of any compensation or other consideration payable or to be received by any officers, directors or employees of any parties to the merger or merger agreement, or any class of such persons, in connection with the merger relative to the merger consideration or otherwise. Jefferies’ opinion was authorized by the Fairness Committee of Jefferies LLC.

In preparing its opinion, Jefferies performed a variety of financial and comparative analyses. The preparation of a fairness opinion is a complex process involving various determinations as to the most appropriate and relevant quantitative and qualitative methods of financial analysis and the applications of those methods to the particular circumstances and, therefore, is not necessarily susceptible to partial analysis or summary description. Jefferies believes that its analyses must be considered as a whole. Considering any portion of Jefferies’ analyses or the factors considered by Jefferies, without considering all analyses and factors, could create a misleading or incomplete view of the process underlying the conclusion expressed in Jefferies’ opinion. In addition, Jefferies may have given various analyses more or less weight than other analyses, and may have deemed various assumptions more or less probable than other assumptions, so that the range of valuations resulting from any particular analysis described below should not be taken to be Jefferies’ view of the merger consideration’s actual value. Accordingly, the conclusions reached by Jefferies were based on all analyses and factors taken as a whole and also on the application of Jefferies’ own experience and judgment.

In performing its analyses, Jefferies made numerous assumptions with respect to industry performance, general business, economic, monetary, regulatory, market and other conditions and other matters, many of which are beyond SemGroup’s, Energy Transfer’s and Jefferies’ control. The analyses performed by Jefferies were not necessarily indicative of actual values or actual future results, which may be significantly more or less favorable

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than suggested by such analyses. In addition, analyses relating to the per share value of SemGroup common stock and per unit value of ET common units does not purport to be an appraisal or to reflect the prices at which the SemGroup common stock or ET common units may actually be sold. The analyses performed were prepared solely as part of Jefferies’ analysis of the fairness, from a financial point of view, of the merger consideration to be received by the Public Common Stock Holders pursuant to the merger agreement to such Public Common Stock Holders, and were provided to the SemGroup board of directors in connection with the delivery of Jefferies’ opinion.

The merger consideration to be received by the Public Common Stock Holders pursuant to the merger agreement was determined through negotiation between SemGroup and Energy Transfer, and the decision by SemGroup to enter into the merger agreement was solely that of the SemGroup board of directors. Jefferies’ opinion and financial analyses were only one of many factors considered by the SemGroup board of directors in its evaluation of the merger and should not be viewed as determinative of the views of the SemGroup board of directors or the management of SemGroup with respect to the merger or the merger consideration.

Analysis of the Merger Consideration

The following is a summary of the material financial and comparative analyses performed by Jefferies in connection with Jefferies’ delivery of its opinion and that was presented to the SemGroup board of directors on September 15, 2019. The financial analyses summarized below include information presented in tabular format. In order to understand fully Jefferies’ analyses, the tables must be read together with the text of each summary. The tables alone do not constitute a complete description of the Jefferies’ analyses. Considering the data described below without considering the full narrative description of Jefferies’ analyses, including the methodologies and assumptions underlying the analyses, could create a misleading or incomplete view of Jefferies’ analyses.

Jefferies expressly consented to the inclusion in the entirety of its opinion as Annex C.

Implied Premia Analysis

Jefferies calculated and compared certain implied transaction premia using the closing price for the shares of SemGroup common stock on September 13, 2019, the closing price for the shares of ET common units on September 13, 2019, and the implied value of the merger consideration to be paid by Energy Transfer for each share of SemGroup common stock pursuant to the merger agreement. For purposes of its analysis, Jefferies calculated an implied value for the merger consideration of $17.00, referred to as the implied merger consideration value, by adding (i) an implied value for the unit consideration per share (calculated by multiplying the exchange ratio of 0.7275 pursuant to the merger agreement by $14.02, the closing price for the ET common units on September 13, 2019), and (ii) the cash consideration of $6.80 per SemGroup share. Jefferies calculated the premium represented by the implied merger consideration value of $17.00 per share of SemGroup common stock relative to:

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The results of these calculations are as follows:

Selected Public Companies Analysis

Using publicly available information, selected analyst reports and information provided by SemGroup and Energy Transfer, Jefferies analyzed (i) the selected financial data of SemGroup with similar data of ten crude oil and refined products public companies that Jefferies judged to be comparable to SemGroup for purposes of its valuation analysis and (ii) the selected financial data of Energy Transfer with similar data of six large cap pipeline public companies that Jefferies judged to be comparable to Energy Transfer for purposes of its valuation analysis. These companies, which are referred to as comparable public companies, were selected because they were deemed to be similar to SemGroup or Energy Transfer, as applicable, in one or more respects, including the nature of their business, size, diversification and financial performance. No specific numeric or other similar criteria were used to select the comparable public companies and all criteria were evaluated in their entirety without application of definitive qualifications or limitations to individual criteria. As a result, a significantly larger or smaller company with substantially similar lines of business and business focus may have been included while a similarly sized company with less similar lines of business and greater diversification may have been excluded. The comparable public companies were:

Comparable public companies with respect to SemGroup:

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Comparable public companies with respect to Energy Transfer:

No comparable public company utilized in the comparable public companies analysis is identical to SemGroup or Energy Transfer. In evaluating the selected comparable public companies, Jefferies made numerous judgments and assumptions with regard to industry performance, general business, economic, market and financial conditions and other matters, many of which are beyond SemGroup’s, Energy Transfer’s and Jefferies’ control. Mathematical analysis, such as determining the median, is not in itself a meaningful method of using comparable company data.

In its analysis, Jefferies derived and compared distribution yields for SemGroup, Energy Transfer and the selected comparable public companies as of September 13, 2019. This analysis indicated the following average and median reference ranges for the benchmarks as set forth below:

Using the reference ranges for the benchmarks set forth below, which ranges were selected by Jefferies in its professional judgment, Jefferies determined implied per share of SemGroup common stock value ranges and implied per ET common unit value ranges as follows:

Using the implied per share of SemGroup common stock value ranges and implied per ET common unit value ranges (multiplied by the exchange ratio), plus the per share cash amount, Jefferies determined ranges of the implied exchange ratio of the value per share of SemGroup common stock to such total merger consideration as follows:

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In its analysis, Jefferies also derived and compared multiples of enterprise value to adjusted EBITDA for SemGroup, Energy Transfer and the selected comparable public companies as of September 13, 2019. This analysis indicated the following average and median reference ranges for the benchmarks as set forth below:

Using the reference ranges for the benchmarks set forth below, which ranges were selected by Jefferies in its professional judgment, Jefferies determined implied per share of SemGroup common stock value ranges and implied per ET common unit value ranges as follows: