(Reuters) – Drugmaker Biogen will buy all of the outstanding shares of Sage Therapeutics it does not already own for $7.22 each, a filing showed on Friday, sending the latter’s shares up 34% in extended trade .

Biogen has a 10.2% stake in Sage Therapeutics, according to the filing. The offer price, which represents a 30% premium to the stock’s close on Friday, values ​​Sage’s equity at $441.7 million, according to Reuters calculations.

Biogen has been navigating a slow recovery in sales of its Alzheimer’s drug Leqembi in the United States after concerns about cost, effectiveness and side effects.

Sage, whose shares fell 74.9% last year, abandoned development of its drug dalzanemdor after multiple test failures. The company said in November that it will focus on its postpartum depression drug, Zurzuvae, which it developed in partnership with Biogen.

In July, Sage also scrapped development of another drug for neurological disorders it was developing with Biogen.

(Reporting by Puyaan Singh in Bangalore; Editing by Alan Barona)