** Shares of drugmaker Sage Therapeutics SAGE.O rise 36.4%
to $7.57 premarket
** Drugmaker Biogen BIIB.O will buy all outstanding shares
of Sage that it does not already own for $7.22 apiece, a filing
showed on Friday
** The offer price, representing a 30% premium to stock's
close on Friday, values Sage's equity at $441.7 mln, according
to Reuters calculations
** Brokerage William Blair says the offer is prudent to
maximize potential for Sage and Biogen's depression drug,
Zurzuvae, without materially impacting Biogen's M&A deal
capacity
** Up to last close, stock down 78.1% in the last 12 months
(Reporting by Christy Santhosh)
((Christy.Santhosh@thomsonreuters.com))