NEW YORK — Bristol-Myers Squibb Co. said Tuesday it will acquire biotechnology partner ZymoGenetics Inc. for $885 million in another move by a major drugmaker to boost its pipeline by snapping up a smaller developer.

The New York drugmaker’s $9.75-per-share bid represents a 77 percent premium to Zymogenetics’ closing price of $5.51. Bristol-Myers’ said the deal is worth $735 million excluding ZymoGenetics’ cash on hand. Both companies have approved the deal, and the board of ZymoGenetics is recommending that shareholders support the bid.

ZymoGenetics stock jumped $4.50, or nearly 85 percent, to $9.76 in aftermarket trading.

Seattle-based ZymoGenetics makes Recothrom, a drug used to reduce bleeding during surgeries. Since January 2009 it has been working with Bristol-Myers to develop a potential hepatitis C treatment called pegylated interferon lambda. That drug is in midstage clinical testing, and the companies said it “could be an important contributor to Bristol-Myers Squibb’s future growth” if it is approved.

“The acquisition of ZymoGenetics brings us full ownership of a promising investigational biologic that strengthens our very diversified Hepatitis C portfolio,” said Lamberto Andreotti, CEO of Bristol-Myers Squibb.