---
schema_version: "secwatch.filing_event.v1"
accession: "0001104659-25-124254"
form_type: "8-K"
ticker: "ENZN"
cik: "0000727510"
company_name: "Viskase Holdings, Inc."
filed_at: "2025-12-23T23:59:59+00:00"
generated_at: "2026-05-16T12:22:20.381891+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.25
calibrated_materiality_score: 0.25
confidence: "high"
source: SEC EDGAR
---

# Enzon Pharmaceuticals extends poison pill expiration to Jan 31, 2026

## Summary
- Sixth Amendment extends Section 382 Rights Agreement Final Expiration Date from Dec 31, 2025 to Jan 31, 2026.
- Rights plan terms otherwise unchanged; adopted to preserve tax attributes under Section 382.
- This is the sixth extension of the original August 2020 rights agreement; prior amendments extended expiration sequentially.
- The amendment was entered into on Dec 23, 2025 between Enzon and Continental Stock Transfer & Trust Company.

## SEC filing metadata
- accession: 0001104659-25-124254
- form_type: 8-K
- ticker: ENZN
- cik: 0000727510
- company_name: Viskase Holdings, Inc.
- filed_at: 2025-12-23T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.25
- calibrated_materiality_score: 0.25
- confidence: high
- sec_items: 1.01, 3.03, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/727510/000110465925124254/0001104659-25-124254-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/727510/000110465925124254/tm2534122d1_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001104659-25-124254
- JSON: https://secwatch.observer/filing/0001104659-25-124254.json
- Plain text: https://secwatch.observer/filing/0001104659-25-124254.txt

## Key facts
- Material Agreements
  Viskase Holdings, Inc. entered into Sixth Amendment with Continental Stock Transfer & Trust Company (effective 2025-12-23).
  - Action: entry
  - Counterparty: Continental Stock Transfer & Trust Company
  - Effective: 2025-12-23
  source text: On December 23, 2025, Enzon Pharmaceuticals, Inc. (the “ Company ”) entered into the Sixth Amendment to the Section 382 Rights Agreement (the “ Sixth Amendment ”), which amends the Section 382 Rights Agreement, dated as of August 14, 2020 (the “ Rights Agreement ”), by and between the Company and Continental Stock Transfer & Trust Company, as rights agent.
  evidence_url: https://www.sec.gov/Archives/edgar/data/727510/000110465925124254/0001104659-25-124254-index.htm

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.