Schedule 13D/A: Tailwater-Related Entities Hold 35.5% of SMC (6.67M Shares)

Rhea-AI Filing Summary

Amendment No. 2 to a Schedule 13D reports that Tailwater-related parties, through Connect Midstream, now beneficially hold 6,670,946 shares of Summit Midstream Corp (SMC), equal to 35.5% of the outstanding common stock on the filing date. The aggregate includes 6,524,467 Common Stock issuable upon conversion of an equivalent number of partnership Common Units and related Class B shares plus 146,479 directly held shares. The filing amends a prior Schedule 13D and notes that recent open-market purchases on 8/26/2025–8/28/2025 totaling 146,479 shares were financed with working capital at average prices of $20.46–$20.89 per share. The document details the ownership chain: Tailwater Energy Fund III LP is sole member of Connect Midstream and identifies the controlling entities and two managing partners who may be deemed to beneficially own the reported securities. The filing is signed 09/02/2025.

Positive

• Material disclosure of ownership: The filing transparently reports a 35.5% aggregate position (6,670,946 shares), giving market clarity on major holder status.
• Recent market purchases disclosed with prices: Purchases on 8/26/2025–8/28/2025 (146,479 shares) reported with average, low, and high prices ($20.46–$20.89), improving transaction transparency.
• Clear ownership chain: The filing explains the relationships among Connect Midstream, Tailwater entities, and named managing partners, aiding governance assessment.

Negative

• Concentrated stake: A single consolidated group controls 35.5% of outstanding common stock, which could materially influence votes or corporate actions.
• Conversion mechanics affect economics and voting: A large portion of the position is issuable upon conversion of partnership units and involves Class B shares that alter voting versus economic interests, complicating shareholder rights analysis.

Insights

Financial Analyst

TL;DR: Tailwater-related entities report a large 35.5% economic and voting stake in SMC, acquired partly via convertible units and recent open-market buys.

The filing discloses a material concentrated position representing 6,670,946 shares or 35.5% of Summit Midstream's common stock on the stated share count basis. The position combines direct common shares and shares issuable upon conversion of partnership common units that confer voting rights through Class B shares. Recent purchases on 8/26–8/28/2025 (146,479 shares) were executed at average prices between $20.46 and $20.89 and financed with working capital. For investors, this level of ownership is sufficiently large to affect control dynamics and voting outcomes; it also creates potential for strategic engagement between the reporting persons and the issuer. The filing properly discloses the ownership chain and conversion mechanics that determine the effective share count.

Corporate Governance Expert

TL;DR: A coordinated Tailwater ownership structure now reports a 35.5% voting position, with conversion features that influence governance rights.

The Schedule 13D/A clarifies that Connect Midstream holds common units and Class B shares that do not convey economic interest but provide voting rights until units convert into common stock, at which point equivalent Class B shares are forfeited. The disclosure of the organizational chain (Tailwater Energy Fund III LP, TW GP EF-III LP, TW GP EF-III GP, LLC, Tailwater Capital LLC) and identifying managing partners makes clear which persons may be deemed beneficial owners for governance purposes. The combination of direct holdings and convertible units concentrated in related entities is material for board elections and shareholder votes; the form and timing of future conversions or purchases will determine evolving control implications.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 2)

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, 2021 McKinney Ave, Suite 1250
Dallas, TX, 75201
(214) 269-8753

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

08/28/2025

(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).

SCHEDULE 13D

CUSIP No. 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 6,670,946.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,670,946.00

11

Aggregate amount beneficially owned by each reporting person

6,670,946.00

12

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

13

Percent of class represented by amount in Row (11)

35.5 %

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 of the Issuer ("Common Stock") 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) 146,479 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 18,766,331 shares of Common Stock outstanding based upon (i) 12,241,864 Common Stock outstanding as of July 31, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 11, 2025, as increased by (ii) 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 No. 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 6,670,946.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,670,946.00

11

Aggregate amount beneficially owned by each reporting person

6,670,946.00

12

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

13

Percent of class represented by amount in Row (11)

35.5 %

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 issuable in respect of an equivalent number of Common Units of the Partnership (as defined below) and Class B Shares beneficially owned by the Reporting Persons and (ii) 146,479 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 18,766,331 shares of Common Stock outstanding based upon (i) 12,241,864 Common Stock outstanding as of July 31, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 11, 2025, as increased by (ii) 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 No. 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 6,670,946.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,670,946.00

11

Aggregate amount beneficially owned by each reporting person

6,670,946.00

12

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

13

Percent of class represented by amount in Row (11)

35.5 %

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 issuable in respect of an equivalent number of Common Units of the Partnership (as defined below) and Class B Shares beneficially owned by the Reporting Persons and (ii) 146,479 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 18,766,331 shares of Common Stock outstanding based upon (i) 12,241,864 Common Stock outstanding as of July 31, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 11, 2025, as increased by (ii) 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 No. 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 6,670,946.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,670,946.00

11

Aggregate amount beneficially owned by each reporting person

6,670,946.00

12

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

13

Percent of class represented by amount in Row (11)

35.5 %

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 issuable in respect of an equivalent number of Common Units of the Partnership (as defined below) and Class B Shares beneficially owned by the Reporting Persons and (ii) 146,479 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 18,766,331 shares of Common Stock outstanding based upon (i) 12,241,864 Common Stock outstanding as of July 31, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 11, 2025, as increased by (ii) 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 No. 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 6,670,946.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,670,946.00

11

Aggregate amount beneficially owned by each reporting person

6,670,946.00

12

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

13

Percent of class represented by amount in Row (11)

35.5 %

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 issuable in respect of an equivalent number of Common Units of the Partnership (as defined below) and Class B Shares beneficially owned by the Reporting Persons and (ii) 146,479 shares of Common Stock beneficially owned by the Reporting Persons. (2) Row 13 is calculated assuming 18,766,331 shares of Common Stock outstanding based upon (i) 12,241,864 Common Stock outstanding as of July 31, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 11, 2025, as increased by (ii) 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 1 Comment: This Amendment No. 2 to Schedule 13D ("Amendment No. 2") amends the Statement on Schedule 13D (as amended, the "Schedule 13D") initially filed on December 3, 2024 with the Securities and Exchange Commission and relates to the Common Stock of Summit Midstream Corporation (the "Issuer").
Item 3.	Source and Amount of Funds or Other Consideration
	Item 3 of the Schedule 13D is hereby amended to include the following at the end thereof: The purchases disclosed in Item 5(c) of this Amendment No. 2 were financed with working capital.
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. 2 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) 146,479 shares of Common Stock directly held by Connect Midstream, which represents 35.5% of the shares of Common Stock outstanding as of the date hereof. Such percentage is calculated assuming 18,766,331 shares of Common Stock outstanding based upon (i) 12,241,864 Common Stock outstanding as of July 31, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 11, 2025, as increased by (ii) 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) 146,479 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. 2 and the information set forth in Item 5(a) of this Amendment No. 2 are each incorporated by reference into this Item 5(b).
(c)	Connect Midstream purchased shares of Common Stock on the public market within the prior 60 days as follows: Date Purchase/(Sale) Amount of Shares Average Price Low Price High Price 8/26/25 Purchase 72,759 $20.46 $19.87 $20.87 8/27/25 Purchase 47,401 $20.50 $20.35 $20.82 8/28/25 Purchase 26,319 $20.89 $20.43 $21.01 The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, full information regarding the number of shares purchased or sold at each separate price within the ranges set forth above. 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.

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:	09/02/2025

Tailwater Energy Fund III LP

Signature:	/s/ Jason H. Downie
Name/Title:	Jason H. Downie/Managing Partner
Date:	09/02/2025

Tailwater Capital LLC

Signature:	/s/ Jason H. Downie
Name/Title:	Jason H. Downie/Managing Partner
Date:	09/02/2025

Jason H. Downie

Signature:	/s/ Jason H. Downie
Name/Title:	Jason H. Downie
Date:	09/02/2025

Edward Herring

Signature:	/s/ Edward Herring
Name/Title:	Edward Herring
Date:	09/02/2025

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 stake does Tailwater/Connect Midstream hold in Summit Midstream (SMC)?

The reporting persons beneficially own 6,670,946 shares, representing 35.5% of SMC common stock on the filing's assumed share count.

How is the 6,670,946-share total composed?

It consists of 6,524,467 shares issuable upon conversion of Common Units and Class B shares plus 146,479 directly held common shares.

When and at what prices were recent purchases made?

Connect Midstream purchased shares on 8/26/2025 (72,759 shares at $20.46 avg), 8/27/2025 (47,401 at $20.50 avg), and 8/28/2025 (26,319 at $20.89 avg).

How were the recent purchases funded?

The filing states the purchases disclosed were financed with working capital.

Who may be deemed to beneficially own the reported securities?

Tailwater Energy Fund III LP, TW GP EF-III LP, TW GP EF-III GP, LLC, Tailwater Capital LLC, and the named managing partners (Jason H. Downie and Edward Herring) are disclosed as parties that may be deemed to beneficially own the reported securities due to their relationships.