Investors that owned shares of Hospira woke up much richer Thursday after Pfizer bought the injectable drugmaker for $90 a share, a premium of nearly 40% from Wednesday night’s close.

Hospira shares (HSP), which closed last night at $64.80 per share, were up  about 35% to $87.40 right after the opening bell.

Pfizer shares (PFE) rose nearly 3% to $32.93.

The Dow Jones industrial average benefited from the rise in Pfizer, which is one of 30 stocks in the Dow. In early trading the blue chip index was up 75 points, or 0.4%, to 17,749.

“The Pfizer-Hospira combination is an excellent strategic fit, presenting a unique opportunity to leverage the complementary strengths of our robust portfolios and rich pipelines,” said F. Michael Ball, the chief executive officer of Hospira.