0000727510
Company
Viskase Holdings, Inc.
Biological Products, (No Diagnostic Substances) · ENZN
follow-on
priced
OTC
425
Filing Timeline
SEC EDGAR
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 425 in the pre-IPO sequence.
2026-03-25 · 0001104659-26-034194
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 425 in the pre-IPO sequence.
2026-03-24 · 0001104659-26-033625
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 425 in the pre-IPO sequence.
2026-03-19 · 0001104659-26-032098
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 425 in the pre-IPO sequence.
2026-03-18 · 0001104659-26-029960
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 425 in the pre-IPO sequence.
2026-03-16 · 0001104659-26-028459
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 425 in the pre-IPO sequence.
2026-03-11 · 0001104659-26-026171
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 424B3 in the pre-IPO sequence.
2026-03-09 · 0001104659-26-025226
424B3
priced
Final prospectus
Final prospectus filed near launch with final deal terms.
Follows 425 and confirms the priced prospectus.
7,935,878 shares
common · Exchange OTC · Use of proceeds to facilitate the merger with Enzon Pharmaceuticals, Inc.
Viskase Holdings, Inc. (formerly Enzon Pharmaceuticals, Inc.) is advancing its merger with Viskase Companies, Inc., as detailed in the 424B3 filing. The prospectus supplement outlines the issuance of up to 7,935,878 shares of common stock in the merger and an exchange offer for Series C preferred stock. Unaudited financial statements for Viskase as of December 31, 2025, are included, reflecting a net loss of $65.66 million for the year. The filing emphasizes the merger's expected closure in 2026, pending regulatory approvals and standard closing conditions.
2026-03-03 · 0001104659-26-022903
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 425 in the pre-IPO sequence.
Enzon Pharmaceuticals, Inc. filed a Form 8-K on February 27, 2026, detailing the Eighth Amendment to its Section 382 Rights Agreement, extending the Final Expiration Date of the exchange offer to March 11, 2026. The filing also includes a press release announcing this extension. The company remains engaged in the merger process with Viskase Companies, Inc., with previous filings confirming stockholder approvals for the merger and reverse stock split.
2026-02-27 · 0001104659-26-021053
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows EFFECT in the pre-IPO sequence.
Enzon Pharmaceuticals, Inc. announced the approval of its consent solicitation for a reverse stock split and a merger with Viskase Companies, Inc. The reverse stock split (1:100) and merger proposal were approved by majority shareholders, with the consent period concluding on February 11, 2026. The transactions remain subject to remaining closing conditions under the merger agreement.
2026-02-11 · 0001104659-26-013514
S-4/A
amended
S-4/A
Pre-IPO filing captured from the SEC submission timeline.
Updates the prior S-4 filing.
Viskase Holdings, Inc. filed an S-4/A registration statement to amend its previous S-4 filing, focusing on the merger between Enzon Pharmaceuticals, Inc. and Viskase Companies, Inc. The amendment includes updated merger agreements, legal documents, and financial disclosures, with an emphasis on regulatory compliance and transactional details. The filing highlights ongoing legal and financial obligations, including credit agreements and rights plans.
2026-01-30 · 0001104659-26-008573
424B3
priced
Final prospectus
Final prospectus filed near launch with final deal terms.
Follows S-4/A and confirms the priced prospectus.
Common Stock
Viskase Holdings, Inc. is finalizing a merger with Enzon Pharmaceuticals, Inc., involving the exchange of Enzon's Series C Preferred Stock for common stock and a reverse stock split. The filing outlines the terms of the merger, including the conversion of Viskase common stock into Enzon shares, the Series C Exchange Offer, and the need for shareholder approvals. The merger requires written consents from Enzon shareholders, with Icahn Enterprises Holdings L.P. (IEH) supporting the transaction.
2026-01-30 · 0001104659-26-008680
EFFECT
effective
SEC effectiveness notice
SEC declared the registration statement effective, allowing the offering to proceed.
Follows 424B3 and marks the registration effective.
Viskase Holdings, Inc. (formerly Enzon Pharmaceuticals, Inc.) filed an S-4 registration statement to effect a merger with Viskase Companies, Inc., resulting in the combined company operating under the Viskase Holdings name. The merger involves a reverse stock split of Enzon's common stock and an exchange of Series C Preferred Stock for common shares. Stockholder consents are being solicited for the merger agreement and reverse stock split, with the IEH Parties providing support. The filing marks the effectiveness of the merger process ahead of the proposed transaction.
2026-01-30 · 9999999995-26-000433
S-4
filed
S-4
Pre-IPO filing captured from the SEC submission timeline.
Follows DRS in the pre-IPO sequence.
Viskase Holdings, Inc. is undergoing a merger with Enzon Pharmaceuticals, Inc., resulting in the combined company operating under the name 'Viskase Holdings, Inc.' The transaction involves a stock exchange offer for Enzon's Series C Preferred Stock, a reverse stock split, and the conversion of Viskase into a limited liability company. The merger requires shareholder approvals and is subject to regulatory conditions.
2026-01-28 · 0001104659-26-007463
DRS
filed
Draft registration statement
Draft registration filed confidentially before the public launch.
Begins the tracked draft filing sequence after 425.
The current filing is a draft registration statement (DRS) for the proposed merger between Enzon Pharmaceuticals, Inc. and Viskase Companies, Inc., resulting in the formation of Viskase Holdings, Inc. The merger involves the exchange of Viskase common stock for Enzon common stock, a reverse stock split, and a Series C preferred stock exchange. Shareholder approvals are required, with the SEC yet to approve the transaction. The previous 425 filing disclosed amendments to the merger terms, including adjusted exchange ratios and an extended termination date.
2025-12-19 · 0001104659-25-123300
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 425 in the pre-IPO sequence.
Viskase Holdings, Inc. (through its subsidiary Enzon Pharmaceuticals) amended its merger agreement with Viskase Companies, Inc. to adjust the exchange ratio, implement a reverse stock split, extend the merger deadline, and modify terms related to material adverse effects. The amendments also involve updated support agreements with Icahn Enterprises Holdings L.P. (IEH) and outline steps for shareholder consents and regulatory filings.
2025-10-24 · 0001104659-25-102131
425
supplemental
425
Pre-IPO filing captured from the SEC submission timeline.
Follows 424B3 in the pre-IPO sequence.
Viskase Holdings, Inc. (formerly Enzon Pharmaceuticals, Inc.) entered into a merger agreement to combine with Viskase Companies, Inc. The merger, structured as a tax-free reorganization, will result in the combined entity operating under the name Viskase Holdings, Inc. and trading on the OTCQX market. The transaction involves the conversion of Viskase shares into Enzon Common Stock, with specific exchange ratios and ownership percentages outlined. The CEO of the combined company will be Timothy P. Feast, and the board will include Jordan Bleznick from Enzon. The merger requires stockholder approvals, regulatory clearances, and other conditions.
2025-06-23 · 0001104659-25-061313
424B3
priced
Final prospectus
Final prospectus filed near launch with final deal terms.
Follows EFFECT and confirms the priced prospectus.
36,056,636 shares · Gross proceeds $0.00
Common Stock · Exchange OTCQX · Ticker ENZN · Selling stockholders only · Use of proceeds Proceeds will go to the selling stockholders, with no proceeds to the company.
The current 424B3 filing relates to the resale of up to 36,056,636 shares of Enzon Pharmaceuticals, Inc. common stock by Icahn Capital LP and affiliates, acquired via a rights offering. The company will not receive proceeds from the resale, which occurs on the OTCQX market. The filing emphasizes risks related to the junior ranking of common stock, potential conflicts with major stockholders, and anti-takeover mechanisms. It also highlights the company's focus on leveraging net operating loss carryforwards through acquisitions.
2020-11-24 · 0001104659-20-129013
EFFECT
effective
SEC effectiveness notice
SEC declared the registration statement effective, allowing the offering to proceed.
Follows S-1 and marks the registration effective.
The current filing is a Notice of Effectiveness for Enzon Pharmaceuticals, Inc.'s S-1 registration statement, effective November 23, 2020. It permits the resale of up to 36,056,636 shares of common stock by selling stockholders, including Icahn Capital LP and affiliates, without the company receiving proceeds. The shares were acquired via open-market purchases, rights offerings, or private placements.
2020-11-23 · 9999999995-20-003279
S-1
filed
Initial registration statement
Initial public filing submitted to start the SEC review process.
Follows 424B3 in the pre-IPO sequence.
36,056,636 shares
Common stock, $0.01 par value per share · Exchange OTCQX · Ticker ENZN · Selling stockholders only · Use of proceeds Selling stockholders will receive all proceeds from the sale of the shares
Enzon Pharmaceuticals, Inc. is a public company acquisition vehicle seeking to leverage its net operating loss carryforwards (NOLs) by acquiring profitable businesses. The current S-1 filing relates to the resale of 36,056,636 shares of common stock by selling stockholders, following a September 2020 rights offering that raised $43.6 million. The company has no clinical operations and relies on licensing agreements, including for Vicineum, which may generate future royalties. The filing emphasizes the risks of uncertain royalty streams and the company's dependence on its NOLs for value creation.
2020-11-12 · 0001104659-20-124408
424B3
priced
Final prospectus
Final prospectus filed near launch with final deal terms.
Follows EFFECT and confirms the priced prospectus.
Viskase Holdings, Inc. is conducting a Rights Offering to distribute subscription rights to existing shareholders, enabling them to purchase units consisting of common stock and Series C Preferred Stock at $1,090 per unit. The offering aims to strengthen the company's capital position, with Icahn Capital LP committing to subscribe for its pro-rata share and any unsubscribed units. The Subscription Rights are transferable but lack a public market, and the Preferred Stock carries a liquidation preference with potential annual adjustments.
2020-09-23 · 0001104659-20-107616
EFFECT
effective
SEC effectiveness notice
SEC declared the registration statement effective, allowing the offering to proceed.
Follows S-1/A and marks the registration effective.
The filing marks the effectiveness of Enzon Pharmaceuticals, Inc.'s S-1 registration statement for a rights offering involving units consisting of preferred and common stock. The offering includes subscription rights for existing shareholders to purchase units at $1,090 per unit, with Icahn Capital LP committing to subscribe for its pro-rata share and purchase unsubscribed units. The Preferred Stock carries a liquidation preference and non-voting rights, with redemption options for the company and holders under specific conditions. The offering is subject to termination, and subscription rights expire on October 9, 2020, unless extended.
2020-09-21 · 9999999995-20-002518
S-1/A
amended
Amended registration statement
Updated registration statement filed after SEC comments or deal changes.
Updates the prior S-1 filing.
Price $1,090 · 40,000 shares · Gross proceeds $43,600,000
Common Stock and Preferred Stock · Each Unit consists of one share of Series C Preferred Stock and 750 shares of Common Stock · Use of proceeds to fund the Rights Offering · Flags units
Enzon Pharmaceuticals, Inc. is conducting a rights offering to distribute transferable subscription rights to purchase units consisting of preferred and common stock. The offering includes a subscription price of $1,090 per unit, with Icahn Capital LP committing to subscribe for its pro-rata share and purchase unsubscribed units. The filing amends the previous S-1 to include specific dates, clarify terms of the preferred stock, and update procedural details.
2020-09-15 · 0001104659-20-105076
S-1
filed
Initial registration statement
Initial public filing submitted to start the SEC review process.
Follows 8-A12B in the pre-IPO sequence.
Price $1,090 · 40,000 shares · Gross proceeds $43,600,000
Subscription Right for every share · Exchange OTCQX · Units, each consisting of (a) one share of $1,000 Par Preferred Stock; and (b) 750 shares of Common Stock · Use of proceeds Proceeds will be used for general corporate purposes
Enzon Pharmaceuticals, Inc. is conducting a Rights Offering to raise up to $43.6 million through the issuance of units consisting of Series C Preferred Stock and common stock. Holders of existing common stock receive transferable subscription rights to purchase these units at $1,090 per unit. The offering includes a commitment from Icahn Capital LP to subscribe for its pro-rata share and purchase unsubscribed units. The Preferred Stock ranks senior to common stock, with specific liquidation preferences and non-convertible terms. The offering is structured to avoid immediate market listing for the units or preferred stock.
2020-09-01 · 0001104659-20-101387
8-A12B
effective
Exchange Act registration
Registration filed to list the securities under the Exchange Act ahead of trading.
Follows EFFECT and registers the class of securities for exchange listing.
Enzon Pharmaceuticals, Inc. registered securities under Section 12(b) of the Exchange Act, implementing a Section 382 rights plan to protect net operating loss carryforwards (NOLs) from limitations due to ownership changes. The plan grants stockholders rights to purchase preferred stock at a set price, exercisable upon a triggering event, with provisions for redemption, exchange, and expiration.
2014-05-01 · 0001144204-14-026849
EFFECT
effective
SEC effectiveness notice
SEC declared the registration statement effective, allowing the offering to proceed.
First tracked pre-IPO filing for this issuer.
The filing represents a Notice of Effectiveness for Enzon Pharmaceuticals Inc.'s Form S-3 registration statement, indicating the SEC has accepted the filing for a securities offering. The effectiveness date is November 3, 2006, with no prior filings referenced.
2006-11-03 · 9999999995-06-002175
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Recent News
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