SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549


SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 19)


VISKASE HOLDINGS, INC.
(Name of Issuer)


Common Stock, par value $0.01 per share
(Title of Class of Securities)


293904108
(CUSIP Numbers)


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)

03/25/2026
(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/A
CUSIP Number(s):
293904108


1 Name of reporting person

CARL C ICAHN
2 Check the appropriate box if a member of a Group (See Instructions)

☐  (a)
☐  (b)
3SEC 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: 13,426,451.00
9 Sole Dispositive Power: 0.00
10 Shared Dispositive Power: 13,426,451.00
11 Aggregate amount beneficially owned by each reporting person

13,426,451.00
12 Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

☐
13 Percent of class represented by amount in Row (11)

93.7 %
14 Type of Reporting Person (See Instructions)

IN



SCHEDULE 13D/A
CUSIP Number(s):
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)
3SEC 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: 13,426,451.00
9 Sole Dispositive Power: 0.00
10 Shared Dispositive Power: 13,426,451.00
11 Aggregate amount beneficially owned by each reporting person

13,426,451.00
12 Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

☐
13 Percent of class represented by amount in Row (11)

93.7 %
14 Type of Reporting Person (See Instructions)

PN



SCHEDULE 13D/A
CUSIP Number(s):
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)
3SEC 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: 13,426,451.00
9 Sole Dispositive Power: 0.00
10 Shared Dispositive Power: 13,426,451.00
11 Aggregate amount beneficially owned by each reporting person

13,426,451.00
12 Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

☐
13 Percent of class represented by amount in Row (11)

93.7 %
14 Type of Reporting Person (See Instructions)

CO




SCHEDULE 13D/A

Item 1.Security and Issuer
(a) Title of Class of Securities:

Common Stock, par value $0.01 per share
(b) Name of Issuer:

VISKASE HOLDINGS, INC.
(c) Address of Issuer's Principal Executive Offices:

333 East Butterfield Road, Suite 400, Lombard, ILLINOIS , 60148.
Item 1 Comment: This statement constitutes Amendment No. 19 to the Schedule 13D relating to the shares of Common Stock, par value $0.01 per share (the "Shares"), issued by Viskase Holdings, Inc. (formerly known as 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: On March 25, 2026, in connection with the closing of the previously announced Merger between the Issuer and Viskase Companies, Inc. ("Viskase") and pursuant to the terms of the IEH Support Agreement, the Reporting Persons exchanged 39,277 shares of Preferred Stock for 5,658,396 shares of the Issuer's Common Stock. On March 26, 2026 (the "Closing Date"), the Issuer completed the Merger with Viskase pursuant to the Merger Agreement. In connection with the Merger and pursuant to the Merger Agreement, the Reporting Persons received 7,407,489 shares of the Issuer in exchange for 150,810,078 shares of Viskase. Robert Flint, Colin Kwak, and Dustin DeMaria were appointed to the Issuer's board of directors in connection with the closing of the Merger. Mr. Flint is the Chief Accounting Officer of Icahn Enterprises L.P. Mr. Kwak is the head trader at Icahn Capital LP, an affiliate of the Reporting Persons. Mr. DeMaria is a Senior Analyst at Ichan Enterprises L.P., an affiliate of the Reporting Persons.
Item 5.Interest in Securities of the Issuer
(a)
Items (a)-(c) of the Original 13D are hereby amended and supplemented as follows: The information set forth in rows 11 and 13 of the cover pages hereto is incorporated herein by reference. The percentages set forth on the cover pages are based on 14,331,713 outstanding Shares as of March 26, 2026, as reported by the Issuer to the Reporting Persons.
(b)
The information set forth in rows 7-10 of the cover pages hereto is incorporated herein by reference.
(c)
The information set forth in Item 4 herein is incorporated herein by reference. Except for the transaction set forth in Item 4, none of the Reporting Persons effected any transaction in the Shares in 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.

 
CARL C ICAHN
 Signature:/s/ Carl C. Icahn
 Name/Title:Carl C. Icahn
 Date:03/27/2026
 
ICAHN ENTERPRISES HOLDINGS L.P.
 Signature:/s/ Ted Papapostolou
 Name/Title:Ted Papapostolou, Chief Financial Officer
 Date:03/27/2026
 
ICAHN ENTERPRISES G.P. INC.
 Signature:/s/ Ted Papapostolou
 Name/Title:Ted Papapostolou, Chief Financial Officer
 Date:03/27/2026