SEMG SemGroup Corporation

SemGroup Corporation

(Name of Registrant as Specified in Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

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.

		Sincerely,
		Thomas R. McDaniel
		Chairman, Board of Directors

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

By Order of the Board of Directors,

SUSAN S. LINDBERG

Executive Vice President and General Counsel

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.

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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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