Zimmer Partners (JRVR) discloses 10% James River ownership and activist intentions

Rhea-AI Filing Summary

Zimmer Partners and affiliated entities have disclosed a large stake in James River Group Holdings, Inc. They report beneficial ownership of 4,623,685 shares of common stock, representing approximately 9.9999987% of James River’s 46,236,856 shares outstanding as of May 4, 2026.

The position, bought for a total of about $22.4 million using the working capital of Zimmer-managed funds and accounts, was acquired because the shares were viewed as undervalued. Zimmer indicates it has begun or may begin discussions with management, the board, and other shareholders on strategic changes, including dividend policy, debt reduction, possible equity private placements, operational changes, expense reductions, securities offerings, and potential strategic transactions. Zimmer may increase or decrease its holdings or use hedging and other transactions as it continues to review its investment.

Insights

Equity analyst

Zimmer’s 10% stake signals active involvement potential but no defined outcome yet.

Zimmer Partners and affiliates report owning 4,623,685 James River shares, about 9.9999987% of the company, purchased for roughly $22.4M. This size positions them as a significant shareholder with substantial influence compared with typical institutional holders.

The filing states that Zimmer believes the stock is undervalued and outlines possible discussions on dividend suspension, debt paydown, private equity placements, and other strategic or operational changes, including potential strategic transactions. These are possibilities rather than announced actions, so their eventual impact is uncertain.

Future developments will depend on how James River’s board and management respond to Zimmer’s proposals and whether Zimmer adjusts its stake. Subsequent company communications or regulatory filings describing concrete steps would clarify how this activist-style position affects James River’s direction.

Key Figures

Shares beneficially owned: 4,623,685 shares Ownership percentage: 9.9999987% Shares outstanding: 46,236,856 shares +3 more

6 metrics

Shares beneficially owned 4,623,685 shares James River common stock held by Zimmer entities

Ownership percentage 9.9999987% Portion of James River common stock outstanding

Shares outstanding 46,236,856 shares James River common stock outstanding as of May 4, 2026

Total purchase price $22,405,043.83 Cost of Zimmer’s James River common stock position

Event date May 14, 2026 Date of event requiring Schedule 13D filing

Par value per share $0.0002 per share Par value of James River common stock

Key Terms

beneficially own, margin accounts, preferred dividend, private placement of equity securities, +1 more

5 terms

beneficially own financial

"Each of the Reporting Persons may be deemed to beneficially own 4,623,685 shares of Common Stock"

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.

margin accounts financial

"purchases of securities through margin accounts maintained for the Zimmer Accounts with brokers"

A margin account is a brokerage account that lets an investor borrow money from the broker to buy more securities than they could with cash alone, using the securities in the account as security for the loan. Think of it like a mortgage for stock purchases: borrowing increases potential gains but also magnifies losses, can trigger a forced sale if the account falls below required limits, and carries interest costs—factors investors must manage carefully.

preferred dividend financial

"elimination of the common dividend and suspension of the preferred dividend"

A preferred dividend is a regular payment that goes first to preferred shareholders before common shareholders receive any payouts. Think of it like having a reserved lane for getting paid: the amount is often fixed and may accumulate if the company skips a payment, giving income-seeking investors more predictability but usually less upside if the company grows rapidly. Investors watch these payments as a sign of a company’s cash commitment and financial stability.

private placement of equity securities financial

"a potential private placement of equity securities, other changes to the Issuer's operations"

strategic transaction financial

"offerings of securities and proposing or responding to a potential strategic transaction"

A strategic transaction is a deliberate business deal—such as a merger, acquisition, divestiture, joint venture or major investment—designed to change a company’s long‑term position, growth path or cost structure. Investors care because these deals can materially alter future revenue, profits and risk exposure; like rearranging pieces on a chessboard, a successful transaction can improve competitive strength and shareholder value, while a poorly executed one can harm them.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

James River Group Holdings, Inc.

(Name of Issuer)

Common Stock, par value $0.0002 per share

(Title of Class of Securities)

46990A102

(CUSIP Number)

Jelena Napolitano
9 West 57th Street, 33rd Floor,
New York, NY, 10019
212-710-4311

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

05/14/2026

(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): 46990A102

1

Name of reporting person

Zimmer Partners, 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)

AF

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 4,623,685.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,623,685.00

11

Aggregate amount beneficially owned by each reporting person

4,623,685.00

12

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

13

Percent of class represented by amount in Row (11)

10 %

14

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP Number(s): 46990A102

1

Name of reporting person

Zimmer Financial Services Group 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)

AF

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 4,623,685.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,623,685.00

11

Aggregate amount beneficially owned by each reporting person

4,623,685.00

12

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

13

Percent of class represented by amount in Row (11)

10 %

14

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13D

CUSIP Number(s): 46990A102

1

Name of reporting person

Zimmer Partners GP, 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)

AF

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 4,623,685.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,623,685.00

11

Aggregate amount beneficially owned by each reporting person

4,623,685.00

12

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

13

Percent of class represented by amount in Row (11)

10 %

14

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13D

CUSIP Number(s): 46990A102

1

Name of reporting person

Stuart J. Zimmer

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)

AF

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 4,623,685.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,623,685.00

11

Aggregate amount beneficially owned by each reporting person

4,623,685.00

12

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

13

Percent of class represented by amount in Row (11)

10 %

14

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.0002 per share
(b)	Name of Issuer: James River Group Holdings, Inc.
(c)	Address of Issuer's Principal Executive Offices: 1414 Raleigh Road, Suite 405, Chapel Hill, NORTH CAROLINA , 27517.
Item 1 Comment: Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable.
Item 2.	Identity and Background
(a)	Zimmer Partners, LP, a Delaware limited partnership (the "Investment Manager"), Zimmer Financial Services Group LLC, a Delaware limited liability company ("ZFSG"), Zimmer Partners GP, LLC, a Delaware limited liability company (the "GP"), and Stuart J. Zimmer, a United States citizen (together with the Investment Manager, ZFSG and the GP, each, a "Reporting Person" and, collectively, the "Reporting Persons").
(b)	The address of the principal business office of each of the Reporting Persons is c/o Zimmer Partners, LP 9 West 57th Street, 33rd Floor New York, NY 10019.
(c)	The principal business of ZFSG is acting as the sole member of the GP and other affiliates. Stuart J. Zimmer, a revocable trust for his benefit, and an irrevocable trust for his immediate family are the sole members of ZFSG. Stuart J. Zimmer's principal business is acting as the Chief Executive Officer of the Investment Manager and ZFSG. The principal business of the GP is acting as the general partner of the Investment Manager. The principal business of the Investment Manager is serving as an investment manager to certain private investment funds and managed accounts, including Zimmer Master Infrastructure Fund, LP and ZP Master MidCap Fund, Ltd., (together, the "Zimmer Accounts"). Jelena Napolitano is the General Counsel of the Investment Manager and Chief Legal Officer of ZFSG, and Neil Adler (together with Ms. Napolitano, the "Specified Officers") is the Chief Financial Officer of the Investment Manager and ZFSG. Except as disclosed herein, none of the Specified Officers beneficially owns any securities of the Issuer (as defined below).
(d)	During the past five years, none of the Reporting Persons nor any of the Specified Officers has been (i) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(e)	During the past five years, none of the Reporting Persons nor any of the Specified Officers has been (i) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(f)	The information in Item 2(a) above is incorporated herein by reference. Each of the Specified Officers is a United States Citizen.
Item 3.	Source and Amount of Funds or Other Consideration
	The Reporting Persons used the working capital of the Zimmer Accounts to purchase the 4,623,685 shares of common stock, par value $0.0002 (the "Common Stock") of James River Group Holdings, Inc. (the "Issuer") reported herein. The total purchase price for such shares of Common Stock reported herein was approximately $22,405,043.83. The Reporting Persons have effected, and may in the future effect, purchases of securities through margin accounts maintained for the Zimmer Accounts with brokers, which extend margin credit as and when required to open or carry positions in their margin accounts, subject to applicable margin regulations, stock exchange rules and such firms' credit policies. Positions in shares of Common Stock may be held in margin accounts and may be pledged as collateral security for the repayment of debit balances in such accounts.
Item 4.	Purpose of Transaction
	The Reporting Persons originally acquired the position in the shares of Common Stock of the Issuer for the account of the Zimmer Accounts in the belief that the shares of Common Stock were undervalued and represented an attractive investment opportunity. The Reporting Persons have begun to discuss or may in the future discuss with management of the Issuer, members of the Issuer's Board of Directors (the "Board") and other stockholders of the Issuer, among other things, strategic changes with respect to the Issuer or its subsidiaries, elimination of the common dividend and suspension of the preferred dividend, use of excess cash to pay down debt, a potential private placement of equity securities, other changes to the Issuer's operations and reduction of expenses, offerings of securities and proposing or responding to a potential strategic transaction. The Reporting Persons intend to review their investment in the Issuer on a continuing basis and may from time to time and at any time in the future depending on various factors, including, without limitation, the Issuer's financial position and strategic direction, actions taken by the Issuer's Board or management, price levels of the shares of Common Stock, other investment opportunities available to the Reporting Persons, conditions in the securities market and general economic and industry conditions, take such actions with respect to their investments in the Issuer as they deem appropriate, including changing its intent with respect to the above. The Reporting Persons may, subject to regulatory approvals: (i) acquire additional shares of Common Stock and/or other equity, debt, notes, other securities, or derivative or other instruments that are convertible into shares of Common Stock, or are based upon or relate to the value of the shares of Common Stock or the Issuer (collectively, "Securities") in the open market, in a private placement, or otherwise; (ii) dispose of any or all of their Securities in the open market or otherwise; (iii) engage in any hedging or similar transactions with respect to the Securities; or (iv) propose or consider one or more of the actions described in subsections (a) through (j) of Item 4 of Schedule 13D.
Item 5.	Interest in Securities of the Issuer
(a)	Each of the Reporting Persons may be deemed to beneficially own 4,623,685 shares of Common Stock of the Issuer, which represents approximately 9.9999987% of the shares of Common Stock outstanding, based on 46,236,856 shares of Common Stock outstanding as of May 4, 2026, as reported in the Issuer's Form 10-Q filed with the Securities and Exchange Commission on May 5, 2026. The shares of Common Stock reported herein are directly held by the Zimmer Accounts. Each Reporting Person may be deemed to beneficially own the shares of Common Stock directly held by the Zimmer Accounts due to their relationships with the Zimmer Accounts as described above in Item 2(a). Such information regarding the relationships among the Reporting Persons in Item 2(a) is incorporated herein by reference.
(b)	Items 7 through 10 of the cover pages of this Schedule 13D for each of the Reporting Persons are incorporated herein by reference.
(c)	Transactions by the Reporting Persons (on behalf of the Zimmer Accounts) effected during the past 60 days are set forth in Exhibit 99.2 and such information is incorporated herein by reference.
(d)	Not applicable.
(e)	Not applicable.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	Not applicable.
Item 7.	Material to be Filed as Exhibits.
	99.1 Agreement Regarding the Joint Filing of Schedule 13D by and among the Reporting Persons 99.2 Transactions Effected by the Reporting Person (on Behalf of the Zimmer Accounts) 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.

Zimmer Partners, LP

Signature:	/s/ Jelena Napolitano
Name/Title:	Jelena Napolitano / Authorized Person
Date:	05/15/2026

Zimmer Financial Services Group LLC

Signature:	/s/ Stuart J. Zimmer
Name/Title:	Stuart J. Zimmer / Director
Date:	05/15/2026

Zimmer Partners GP, LLC

Signature:	/s/ Stuart J. Zimmer
Name/Title:	Stuart J. Zimmer / Director, Zimmer Financial Services Group LLC
Date:	05/15/2026

Stuart J. Zimmer

Signature:	/s/ Stuart J. Zimmer
Name/Title:	Stuart J. Zimmer / Self
Date:	05/15/2026

FAQ

What did Zimmer Partners disclose about its stake in James River (JRVR)?

Zimmer Partners and related entities disclosed beneficial ownership of James River common stock. They report holding 4,623,685 shares, representing about 9.9999987% of the company’s outstanding shares, making them a significant shareholder with potential influence over future strategic discussions.

How many James River (JRVR) shares does Zimmer own and what percentage is this?

Zimmer entities report beneficial ownership of 4,623,685 James River shares. This represents approximately 9.9999987% of the 46,236,856 common shares outstanding as of May 4, 2026, according to James River’s Form 10-Q referenced in the disclosure.

How much did Zimmer pay for its James River (JRVR) position?

Zimmer reports a total purchase price of about $22,405,043.83 for its James River common stock. The shares were bought for Zimmer-managed funds and accounts using working capital, with the possibility of using margin accounts subject to broker and regulatory requirements.

Why did Zimmer Partners invest in James River (JRVR) stock?

Zimmer states it acquired James River shares because it believed the common stock was undervalued and an attractive investment opportunity. The firm’s Schedule 13D indicates this value-oriented thesis underpins its approximately 10% beneficial ownership position in the company.

What strategic changes might Zimmer seek at James River (JRVR)?

Zimmer may discuss strategic changes including eliminating the common dividend, suspending the preferred dividend, using excess cash to repay debt, potential private equity placements, operational and expense reductions, securities offerings, and possible strategic transactions, according to the detailed intentions outlined in the filing.

Can Zimmer change its James River (JRVR) stake going forward?

Yes. Zimmer indicates it may acquire additional James River securities, dispose of some or all holdings, or engage in hedging and related transactions. Any changes will depend on factors such as James River’s financial position, share price, board actions, market conditions, and other investment opportunities.

How was Zimmer’s James River (JRVR) investment financed and held?

The investment was funded with working capital from Zimmer-managed private funds and accounts. The filing notes that positions in James River shares may be held in margin accounts with brokers, where shares can be pledged as collateral for debit balances under applicable margin rules and firm policies.