Pliant and Acelyrin Adopt Poison Pill Defenses Against Potential Concentra Buyout

Both Pliant Therapeutics and Acelyrin have implemented "poison pill" provisions to protect against potential hostile takeover attempts by Concentra Biosciences, controlled by activist investor Kevin Tang36.

Acelyrin's poison pill is triggered if an investor acquires 10% or more of the company's outstanding common stock, or 20% beneficial ownership3.

Pliant's poison pill allows shareholders to purchase additional shares at a 50% discount if an unapproved company acquires 10% or more of Pliant's stock6.

Tang Capital Partners currently owns 8.8% of Acelyrin and 9.6% of Pliant, just below the 10% threshold set in the poison pill provisions6.

Acelyrin recently rejected a buyout offer from Concentra Biosciences, opting to proceed with its planned merger with Alumis17.

Pliant has faced recent setbacks, including the discontinuation of its Phase IIb/III BEACON-IPF study for bexotegrast in idiopathic pulmonary fibrosis6.

The poison pill defenses are seen as a response to Tang Capital's history of aggressive moves to acquire struggling biotechs6.

Both companies' stock rights plans are set to expire in 2026, with Pliant's expiring on March 11, 202636.

Sources:

1. https://www.fiercebiotech.com/biotech/acelyrin-doubles-down-alumis-merger-after-deciding-concentras-surprise-offer-isnt-better

3. https://www.bizjournals.com/sanfrancisco/news/2025/03/13/poison-pill-acelyrin-alumis-pliant-tang-capital.html

6. https://www.biospace.com/business/pliant-pops-poison-pill-as-concentra-threat-looms

7. https://www.biospace.com/business/acelyrin-rejects-concentras-buyout-offer-in-favor-of-alumis-merger