Icahn backs Enzon merger with 48.6% stake

Carl Icahn and his affiliated entities report a 48.6% stake in Enzon Pharmaceuticals, Inc., holding 36,056,636 shares of common stock with shared voting and dispositive power.

Rhea-AI Filing Summary

Carl Icahn and his affiliated entities report a 48.6% stake in Enzon Pharmaceuticals, Inc., holding 36,056,636 shares of common stock with shared voting and dispositive power. The filing is Amendment No. 18 to their Schedule 13D on Enzon.

Icahn, Icahn Enterprises Holdings L.P., and Icahn Enterprises G.P. Inc. each report the same 36,056,636 shares as beneficially owned, with no sole voting or dispositive power. The filing notes they may also be deemed to beneficially own shares of preferred stock, though those are not quantified here.

Under a previously disclosed IEH Support Agreement among Icahn Enterprises Holdings affiliates, Enzon and Viskase, Icahn-affiliated holders delivered a written consent on January 30, 2026 approving a proposed merger and an amendment to Enzon’s certificate of incorporation, using all Enzon shares they hold.

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Icahn uses a 48.6% stake to formally approve Enzon’s merger and charter changes.

The filing shows Carl Icahn and key Icahn entities collectively beneficially own 36,056,636 Enzon common shares, or 48.6% of the class. All voting and dispositive power is reported as shared, reflecting coordinated control across Icahn-controlled entities rather than personal holdings alone.

Through the IEH Support Agreement involving Icahn Enterprises Holdings, Enzon and Viskase, Icahn affiliates delivered a written consent on January 30, 2026. That consent approves the merger and an amendment to Enzon’s certificate of incorporation using all Icahn-held Enzon shares, providing decisive support for the transaction.

This written consent is significant because it comes from a near‑majority holder, making approval of the merger and charter amendment largely a function of implementation steps already defined in company agreements and subsequent corporate actions disclosed in future filings.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How much of Enzon Pharmaceuticals (ENZN) does Carl Icahn currently beneficially own?

Carl Icahn and his affiliated entities report beneficial ownership of 36,056,636 shares of Enzon common stock, representing 48.6% of the outstanding class. All of these shares are reported with shared voting and dispositive power rather than sole control.

What corporate action did Icahn’s group take in this Enzon (ENZN) Schedule 13D/A amendment?

Icahn-affiliated holders delivered a written consent on January 30, 2026 approving Enzon’s proposed merger and an amendment to its certificate of incorporation. The consent covers all Enzon shares held by those Icahn affiliates under the IEH Support Agreement.

Which entities related to Carl Icahn are reporting ownership in Enzon (ENZN)?

The reporting persons are Carl C. Icahn, Icahn Enterprises Holdings L.P., and Icahn Enterprises G.P. Inc.. Each reports beneficial ownership of 36,056,636 Enzon common shares with shared voting and shared dispositive power, reflecting coordinated control.

Does Icahn’s group indicate any preferred stock interests in Enzon (ENZN)?

Each reporting person notes they may also be deemed to beneficially own shares of preferred stock. The filing does not specify the number of preferred shares, but clarifies this possible additional beneficial ownership alongside the disclosed common stock stake.

What is the significance of the IEH Support Agreement mentioned in the Enzon (ENZN) filing?

Under the IEH Support Agreement among Icahn Enterprises Holdings affiliates, Enzon and Viskase, Icahn affiliates agreed on how to vote their shares. Pursuant to that agreement, they delivered a written consent approving the merger and charter amendment on January 30, 2026.

What voting power does Icahn’s group report over Enzon (ENZN) common stock?

Each reporting person discloses 0 shares with sole voting power and 36,056,636 shares with shared voting power. They likewise report 0 shares with sole dispositive power and 36,056,636 shares with shared dispositive power over Enzon common stock.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 01/30/2026 - 06:02 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 18)

ENZON PHARMACEUTICALS, INC.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

293904108

(CUSIP Number)

Jesse Lynn, Esq.
Icahn Capital LP, 16690 Collins Avenue, Suite PH-1
Sunny Isles Beach, FL, 33160
305-442-4000

Joshua Apfelroth
Proskauer Rose LLP, Eleven Times Square
New York, NY, 10036
212-969-3000

Louis Rambo
Proskauer Rose LLP, 1001 Pennsylvania Ave. NW, Suite 600
Washington, DC, 20004
202-416-6800

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

01/30/2026

(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).

SCHEDULE 13D

CUSIP No. 293904108

1

Name of reporting person

CARL C ICAHN

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 36,056,636.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 36,056,636.00

11

Aggregate amount beneficially owned by each reporting person

36,056,636.00

12

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

13

Percent of class represented by amount in Row (11)

48.6 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

The Reporting Person may also be deemed to beneficially own shares of Preferred Stock.

SCHEDULE 13D

CUSIP No. 293904108

1

Name of reporting person

ICAHN ENTERPRISES HOLDINGS L.P.

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 36,056,636.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 36,056,636.00

11

Aggregate amount beneficially owned by each reporting person

36,056,636.00

12

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

13

Percent of class represented by amount in Row (11)

48.6 %

14

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person:

The Reporting Person may also be deemed to beneficially own shares of Preferred Stock.

SCHEDULE 13D

CUSIP No. 293904108

1

Name of reporting person

ICAHN ENTERPRISES G.P. INC.

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 36,056,636.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 36,056,636.00

11

Aggregate amount beneficially owned by each reporting person

36,056,636.00

12

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

13

Percent of class represented by amount in Row (11)

48.6 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

The Reporting Person may also be deemed to beneficially own shares of Preferred Stock.

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: ENZON PHARMACEUTICALS, INC.
(c)	Address of Issuer's Principal Executive Offices: 20 Commerce Drive (Suite 135), Cranford, NEW JERSEY , 07016.
Item 1 Comment: This statement constitutes Amendment No. 18 to the Schedule 13D relating to the shares of Common Stock, par value $0.01 per share (the "Shares"), issued by Enzon Pharmaceuticals, Inc., a Delaware corporation (the "Issuer"), and amends the Schedule 13D relating to the Shares filed on March 14, 2008 (as previously amended, the "Original 13D"), on behalf of the Reporting Persons (as defined in Item 2 of Amendment No. 16 to the Schedule 13D). Capitalized terms used herein and not otherwise defined have the respective meanings ascribed thereto in the Original 13D.
Item 4.	Purpose of Transaction
	Item 4 of the Original 13D is hereby amended and supplemented as follows: The disclosure set forth in Item 6 of this Schedule 13D is incorporated herein by reference.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	Item 6 of the Original 13D is hereby amended and supplemented as follows: Pursuant to the previously disclosed IEH Support Agreement by and between Icahn Enterprises Holdings and certain of its affiliates, the Issuer and Viskase, on January 30, 2026, affiliates of Icahn Enterprises Holdings delivered to the Issuer a wirtten consent with respect to all of the issued and outstanding Shares held by such affiliates approving the Merger and the amendment to the Issuer's certificate of incorporation.

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.

CARL C ICAHN

Signature:	/s/ Carl C. Icahn
Name/Title:	Carl C. Icahn
Date:	01/30/2026

ICAHN ENTERPRISES HOLDINGS L.P.

Signature:	/s/ Ted Papapostolou
Name/Title:	Ted Papapostolou, Chief Financial Officer
Date:	01/30/2026

ICAHN ENTERPRISES G.P. INC.

Signature:	/s/ Ted Papapostolou
Name/Title:	Ted Papapostolou, Chief Financial Officer
Date:	01/30/2026