Tailwater group takes 39.1% Summit Midstream (SMC) stake after $42M share issue

Rhea-AI Filing Summary

Connect Midstream and affiliated Tailwater entities report a 39.1% beneficial stake in Summit Midstream Corp following a recent equity issuance. They report beneficial ownership of 7,891,864 shares of common stock, including 6,524,467 shares issuable upon conversion of an equivalent number of Common Units and associated Class B shares, and 1,367,397 shares directly held by Connect Midstream.

The ownership percentage is based on 20,185,604 shares outstanding, which includes 12,440,219 shares outstanding as of March 13, 2026, 1,220,918 shares issued on March 31, 2026, and the 6,524,467 issuable shares. The filing describes a Securities Purchase Agreement under which Summit agreed to issue 1,351,351 shares of common stock to Tall Oak Parent for $42,000,000 in cash at $31.08 per share, the New York Stock Exchange “Minimum Price,” with the shares treated as registerable securities under an amended Investor Agreement.

Insights

Equity ownership and capital-raising analyst

Tailwater-linked entities now control about 39% of Summit Midstream after a $42M equity issuance at $31.08 per share.

The filing shows Connect Midstream and affiliated Tailwater entities beneficially owning 7,891,864 shares of Summit Midstream, or about 39.1% of the common stock. Most of this comes from 6,524,467 Common Units and paired Class B shares that are convertible into common stock, plus 1,367,397 shares already held.

The amendment also details a $42,000,000 cash investment via 1,351,351 newly issued shares at $31.08 per share, described as the New York Stock Exchange “Minimum Price.” This strengthens the company’s equity base while concentrating ownership with a single sponsor group that has shared voting and dispositive power over the position.

The Purchase Agreement and related Investor Agreement amendment provide registration rights for the new shares, allowing for potential resale under a future registration statement. Actual market impact will depend on future conversion of Common Units and any resales made under those registration rights as disclosed in later filings.

Key Figures

Beneficial ownership: 7,891,864 shares Ownership percentage: 39.1% Issuable upon conversion: 6,524,467 shares +5 more

8 metrics

Beneficial ownership 7,891,864 shares Shares of common stock beneficially owned by reporting persons

Ownership percentage 39.1% Percent of Summit Midstream common stock represented by reported holdings

Issuable upon conversion 6,524,467 shares Common stock issuable from Common Units and Class B shares

Directly held shares 1,367,397 shares Common stock directly held by Connect Midstream

Total shares assumed outstanding 20,185,604 shares Share count used to compute 39.1% ownership

New shares issued 1,351,351 shares Common stock issued to Tall Oak Parent under Purchase Agreement

Equity investment $42,000,000 Cash paid for 1,351,351 newly issued shares

Issue price $31.08 per share Price per share, described as NYSE “Minimum Price”

Key Terms

beneficially own, Common Units, Class B Shares, Registerable Securities, +2 more

6 terms

beneficially own financial

"each of the foregoing may be deemed to beneficially own the reported securities"

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

Common Units financial

"6,524,467 shares of Common Stock issuable in respect of an equivalent number of Common Units"

Common units are the basic ownership stakes in a company, limited partnership, or trust that function like common stock: they give holders a claim on profits and often voting rights. Think of them as the ordinary seats at a table—the most directly affected by the business’s success or failure, so they typically offer higher upside but carry greater risk than preferred claims or creditors, which matters to investors evaluating potential return and safety.

Class B Shares financial

"6,524,467 Class B Shares, which do not represent an economic interest in the Issuer"

Class B shares are one type of a company’s stock that carries a specific set of rights — often different voting power or dividend rules compared with other classes. For investors, that affects influence over company decisions and potential income: owning Class B might mean fewer or more votes per share or different claim on profits, like having a different seat at a decision table or a different slice of the payout pie.

Registerable Securities financial

"the Shares issued to Tall Oak Parent constitute "Registerable Securities" under the Investor Agreement"

Minimum Price financial

"issued at a price of $31.08 per share, which represents the "Minimum Price" in accordance with New York Stock Exchange regulations"

Securities Purchase Agreement financial

"Pursuant to the Securities Purchase Agreement (the "Purchase Agreement"), by and among the Company"

A securities purchase agreement is a written contract between a buyer and a seller outlining the terms for buying or selling financial assets such as stocks or bonds. It specifies details like the price, quantity, and conditions of the transaction, similar to a shopping list with agreed-upon terms. For investors, it provides clarity and legal protection when transferring ownership of these financial instruments.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 3)

Summit Midstream Corp

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

86614G101

(CUSIP Number)

Brian Blakeman
c/o Connect Midstream, LLC, 4020 Maple Ave, Suite 200
Dallas, TX, 75219
(214) 269-8753

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

03/31/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 86614G101

1

Name of reporting person

Connect Midstream, LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 7,891,864.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 7,891,864.00

11

Aggregate amount beneficially owned by each reporting person

7,891,864.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

39.1 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

(1) Row 11 represents (i) 6,524,467 shares of common stock ("Common Stock") of the Issuer issuable in respect of an equivalent number of common units ("Common Units") of the Partnership (as defined below) and class B common stock of the Issuer ("Class B Shares") beneficially owned by the Reporting Persons and (ii) 1,367,397 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 20,185,604 shares of Common Stock outstanding based upon (i) 12,440,219 shares of Common Stock outstanding as of March 13, 2026, as reported in the Issuer's Annual Report on Form 10-K filed with the SEC on March 16, 2026, as increased by (ii) the 1,220,918 shares of Common Stock issued to the Reporting Person on March 31, 2026 and (iii) 6,524,467 shares of Common Stock issuable in respect of an equivalent number of Common Units and Class B Shares beneficially owned by the Reporting Persons.

SCHEDULE 13D

CUSIP Number(s): 86614G101

1

Name of reporting person

Tailwater Energy Fund III LP

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 7,891,864.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 7,891,864.00

11

Aggregate amount beneficially owned by each reporting person

7,891,864.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

39.1 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person:

(1) Row 11 represents (i) 6,524,467 shares of common stock ("Common Stock") of the Issuer issuable in respect of an equivalent number of common units ("Common Units") of the Partnership (as defined below) and class B common stock of the Issuer ("Class B Shares") beneficially owned by the Reporting Persons and (ii) 1,367,397 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 20,185,604 shares of Common Stock outstanding based upon (i) 12,440,219 shares of Common Stock outstanding as of March 13, 2026, as reported in the Issuer's Annual Report on Form 10-K filed with the SEC on March 16, 2026, as increased by (ii) the 1,220,918 shares of Common Stock issued to the Reporting Person on March 31, 2026 and (iii) 6,524,467 shares of Common Stock issuable in respect of an equivalent number of Common Units and Class B Shares beneficially owned by the Reporting Persons.

SCHEDULE 13D

CUSIP Number(s): 86614G101

1

Name of reporting person

Tailwater Capital LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 7,891,864.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 7,891,864.00

11

Aggregate amount beneficially owned by each reporting person

7,891,864.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

39.1 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

(1) Row 11 represents (i) 6,524,467 shares of common stock ("Common Stock") of the Issuer issuable in respect of an equivalent number of common units ("Common Units") of the Partnership (as defined below) and class B common stock of the Issuer ("Class B Shares") beneficially owned by the Reporting Persons and (ii) 1,367,397 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 20,185,604 shares of Common Stock outstanding based upon (i) 12,440,219 shares of Common Stock outstanding as of March 13, 2026, as reported in the Issuer's Annual Report on Form 10-K filed with the SEC on March 16, 2026, as increased by (ii) the 1,220,918 shares of Common Stock issued to the Reporting Person on March 31, 2026 and (iii) 6,524,467 shares of Common Stock issuable in respect of an equivalent number of Common Units and Class B Shares beneficially owned by the Reporting Persons.

SCHEDULE 13D

CUSIP Number(s): 86614G101

1

Name of reporting person

Jason H. Downie

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 7,891,864.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 7,891,864.00

11

Aggregate amount beneficially owned by each reporting person

7,891,864.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

39.1 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

(1) Row 11 represents (i) 6,524,467 shares of common stock ("Common Stock") of the Issuer issuable in respect of an equivalent number of common units ("Common Units") of the Partnership (as defined below) and class B common stock of the Issuer ("Class B Shares") beneficially owned by the Reporting Persons and (ii) 1,367,397 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 20,185,604 shares of Common Stock outstanding based upon (i) 12,440,219 shares of Common Stock outstanding as of March 13, 2026, as reported in the Issuer's Annual Report on Form 10-K filed with the SEC on March 16, 2026, as increased by (ii) the 1,220,918 shares of Common Stock issued to the Reporting Person on March 31, 2026 and (iii) 6,524,467 shares of Common Stock issuable in respect of an equivalent number of Common Units and Class B Shares beneficially owned by the Reporting Persons.

SCHEDULE 13D

CUSIP Number(s): 86614G101

1

Name of reporting person

Edward Herring

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 7,891,864.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 7,891,864.00

11

Aggregate amount beneficially owned by each reporting person

7,891,864.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

39.1 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

(1) Row 11 represents (i) 6,524,467 shares of common stock ("Common Stock") of the Issuer issuable in respect of an equivalent number of common units ("Common Units") of the Partnership (as defined below) and class B common stock of the Issuer ("Class B Shares") beneficially owned by the Reporting Persons and (ii) 1,367,397 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 20,185,604 shares of Common Stock outstanding based upon (i) 12,440,219 shares of Common Stock outstanding as of March 13, 2026, as reported in the Issuer's Annual Report on Form 10-K filed with the SEC on March 16, 2026, as increased by (ii) the 1,220,918 shares of Common Stock issued to the Reporting Person on March 31, 2026 and (iii) 6,524,467 shares of Common Stock issuable in respect of an equivalent number of Common Units and Class B Shares beneficially owned by the Reporting Persons.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.01 per share
(b)	Name of Issuer: Summit Midstream Corp
(c)	Address of Issuer's Principal Executive Offices: 901 Louisiana Street, Suite 4200, Houston, TEXAS , 77002.
Item 4.	Purpose of Transaction
	Item 4 of the Schedule 13D is hereby amended to include the following at the end thereof: Securities Purchase Agreement Pursuant to the Securities Purchase Agreement (the "Purchase Agreement"), by and among the Company, the Partnership, and Tall Oak Parent, and solely for purposes of modifying certain existing registration rights as detailed in the Purchase Agreement, Connect Midstream, LLC, a Delaware limited liability company ("Connect Midstream"), the Company agreed to issue and sell to Tall Oak Parent (or its designated members) 1,351,351 shares (the "Shares") of Common Stock in exchange for $42,000,000 in cash. The Purchase Agreement contained customary representations, warranties, covenants, conditions to closing, and termination provisions. Upon consummation of the foregoing, the reported securities were distributed by Tall Oak Parent to Connect Midstream. The foregoing description of the Purchase Agreement does not purport to be complete and is qualified in its entirety by the full text of the Purchase Agreement, a copy of which is filed as Exhibit 10.1 to the Issuer's current report on Form 8-K filed with the SEC on April 2, 2026, and is incorporated herein by reference. Investor Agreement Amendment The Purchase Agreement amends and modifies the Investor Agreement such that, among other things, the Shares issued to Tall Oak Parent constitute "Registerable Securities" under the Investor Agreement, and, pursuant to the terms of the Purchase Agreement and the Investor Agreement, the Company will use commercially reasonable efforts to prepare and file a Registration Statement (as defined in the Investor Agreement) with the SEC (or amend by post-effective amendment a previously filed Registration Statement, covering the resale of all of the Shares for an offering to be made on a continuous basis pursuant to Rule 415 under the Securities Act of 1933, as amended (the "Securities Act"), within 90 days of the closing of the transaction. The foregoing description of the Investor Agreement does not purport to be complete and is qualified in its entirety by the full text of the Investor Agreement, a copy of which is filed as Exhibit 10.2 to the Issuer's current report on Form 8-K filed with the SEC on December 3, 2024 and is incorporated herein by reference.
Item 5.	Interest in Securities of the Issuer
(a)	The information set forth in rows eleven and thirteen on the cover pages of this Amendment No. 3 is incorporated by reference into this Item 5(a). The reported securities represent (i) 6,524,467 shares of Common Stock issuable in respect of an equivalent number of Common Units and Class B Shares beneficially owned by the Reporting Persons and (ii) 1,367,397 shares of Common Stock directly held by Connect Midstream, which represents approximately 39.1% of the shares of Common Stock outstanding as of the date hereof. Such percentage is calculated assuming assuming 20,185,604 shares of Common Stock outstanding based upon (i) 12,440,219 shares of Common Stock outstanding as of March 13, 2026, as reported in the Issuer's Annual Report on Form 10-K filed with the SEC on March 16, 2026, as increased by (ii) the 1,220,918 shares of Common Stock issued to the Reporting Person on March 31, 2026 and (iii) 6,524,467 shares of Common Stock issuable in respect of an equivalent number of Common Units and Class B Shares beneficially owned by the Reporting Persons. In this regard, Connect Midstream is the direct holder of (i) 6,524,467 Common Units which are convertible into an equivalent number of shares of Common Stock and the direct holder of (ii) 1,367,397 shares of Common Stock. Connect Midstream is also the direct holder of 6,524,467 Class B Shares, which do not represent an economic interest in the Issuer but provide holders of Common Units with voting rights. Upon conversion of Common Units into shares of Common Stock, an equivalent number of Class B Shares are forfeited for no consideration. Tailwater Energy is the sole member of Connect Midstream. TW GP EF-III LP is the general partner of Tailwater Energy. TW GP EF-III GP, LLC is the general partner of TW GP EF-III LP. Tailwater Capital LLC is the sole member of TW GP EF-III GP, LLC. Jason H. Downie and Edward Herring are both Managing Partners of Tailwater Capital. As a result of these relationships, each of the foregoing may be deemed to beneficially own the reported securities, provided that neither the filing of this Schedule 13D nor any of its contents shall be deemed to constitute an admission by any of the Reporting Persons or any of the foregoing that it is the beneficial owner of any of the Common Stock referred to herein for the purposes of Section 13(d) of the Act, or for any other purpose.
(b)	The information set forth in rows seven through ten on the cover pages of this Amendment No. 3 and the information set forth in Item 5(a) of this Amendment No. 3 are each incorporated by reference into this Item 5(b).
(c)	The information contained in Item 4 of this Schedule 13D is hereby incorporated by reference into this Item 6. The shares of Common Stock were issued at a price of $31.08 per share, which represents the "Minimum Price" in accordance with New York Stock Exchange regulations. Except for the foregoing or as otherwise set forth herein, each of the Reporting Persons reports that neither it, nor to its knowledge, any other person named in Item 2 of the Schedule 13D, has effected any transactions in Common Stock during the past 60 days.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	The information contained in Item 4 of this Schedule 13D is hereby incorporated by reference into this Item 6.
Item 7.	Material to be Filed as Exhibits.
	Item 10 of the Schedule 13D is hereby amended to include the following at the end thereof: Exhibit 10.3 Securities Purchase Agreement, by and among Summit Midstream Corporation, Summit Midstream Partners, LP, Tall Oak Midstream Holdings, LLC and Connect Midstream, LLC, dated as of March 31, 2026, filed as Exhibit 10.1 to the Issuer's current report on Form 8-K filed with the SEC on April 2, 2026, and incorporated herein by reference.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Connect Midstream, LLC

Signature:	/s/ Jason H. Downie
Name/Title:	Jason H. Downie/Director
Date:	04/09/2026

Tailwater Energy Fund III LP

Signature:	/s/ Jason H. Downie
Name/Title:	Jason H. Downie/Managing Partner
Date:	04/09/2026

Tailwater Capital LLC

Signature:	/s/ Jason H. Downie
Name/Title:	Jason H. Downie/Managing Partner
Date:	04/09/2026

Jason H. Downie

Signature:	/s/ Jason H. Downie
Name/Title:	Jason H. Downie
Date:	04/09/2026

Edward Herring

Signature:	/s/ Edward Herring
Name/Title:	Edward Herring
Date:	04/09/2026

Comments accompanying signature:

Tailwater Energy Fund III LP is the sole member of Connect Midstream, LLC. TW GP EF-III LP is the general partner of Tailwater Energy Fund III LP. TW GP EF-III GP, LLC is the general partner of TW GP EF-III LP. Tailwater Capital LLC is the sole member of TW GP EF-III GP, LLC. Jason H. Downie and Edward Herring are each a Managing Partner of Tailwater Capital LLC.

FAQ

What percentage of Summit Midstream Corp (SMC) does Connect Midstream now beneficially own?

Connect Midstream and affiliated Tailwater entities report beneficial ownership of about 39.1% of Summit Midstream’s common stock. This equals 7,891,864 shares based on a total of 20,185,604 shares of common stock outstanding using the filing’s detailed share count assumptions.

How many Summit Midstream (SMC) shares are held or issuable to the Tailwater-related group?

The group reports 7,891,864 shares beneficially owned. This consists of 6,524,467 shares of common stock issuable upon conversion of an equivalent number of Common Units and Class B shares, plus 1,367,397 shares of common stock directly held by Connect Midstream.

What equity transaction added to Summit Midstream’s capital in this Schedule 13D/A?

Summit Midstream agreed to issue and sell 1,351,351 shares of common stock to Tall Oak Parent for $42,000,000 in cash. This share issuance increased total outstanding shares and formed part of the ownership position later distributed to Connect Midstream under the Purchase Agreement.

At what price were the new Summit Midstream (SMC) shares issued to Tall Oak Parent?

The shares were issued at $31.08 per share, described as the “Minimum Price” under New York Stock Exchange regulations. This pricing applied to the 1,351,351 shares of common stock issued for $42,000,000 in cash under the Securities Purchase Agreement.

How was the 39.1% ownership stake in Summit Midstream (SMC) calculated?

The 39.1% figure assumes 20,185,604 shares of common stock outstanding. That total includes 12,440,219 shares outstanding on March 13, 2026, plus 1,220,918 shares issued on March 31, 2026, and 6,524,467 shares issuable upon conversion of Common Units and associated Class B shares.

What registration rights do the new Summit Midstream shares receive under the Investor Agreement?

The amendment treats the newly issued shares as “Registerable Securities” under the Investor Agreement. Summit Midstream will use commercially reasonable efforts to file or amend a registration statement with the SEC covering resale of all such shares on a continuous basis, subject to that agreement’s terms.