Regulation FD Disclosure (Form 8-K)

On March 9, 2026, the Company issued a press release announcing an extension to the expiration date for the exchange offer (the "Offer") by the Company to each holder of its Series C Non-Convertible Redeemable Preferred Stock, $0.01 par value per share (the "Series C Preferred Stock"), to exchange such Series C Preferred Stock for shares of Enzon's common stock, $0.01 par value per share. After giving effect to the extension, the Offer expires one minute after 11:59 p.m., Eastern time, on March 11, 2026, unless the Offer is further extended. A copy of the press release is attached as Exhibit 99.1 hereto and incorporated herein by reference.

In accordance with General Instruction B.2 of Form 8-K, the foregoing information, including Exhibit 99.1, shall not be deemed "filed" for the purposes of Section 18 of the Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall such information, including Exhibit 99.1, be deemed incorporated by reference into any filing under the Securities Act or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Important Information About the Merger and Where to Find It

In connection with the proposed transactions between Enzon and Viskase Companies, Inc. ("Viskase"), Enzon filed a registration statement on Form S-4 with the SEC that contains a prospectus, consent solicitation statement and offer to exchange (the "Registration Statement"). The Registration Statement includes financial information regarding the combined company. This communication is not a substitute for the Registration Statement or any other documents that Enzon may file with the SEC or that Enzon or Viskase may send to their respective stockholders in connection with the transactions contemplated by the Merger Agreement.

You may obtain free copies of the Registration Statement and all other documents filed or that will be filed with the SEC regarding the proposed transaction at the website maintained by the SEC at www.sec.gov. The Registration Statement is available free of charge on Enzon's website at https://www.enzon.com.

No Offer or Solicitation

This communication is not intended to be, and shall not constitute, an offer to sell or the solicitation of an offer to buy or sell any securities or a solicitation of any vote or approval, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended.