Pfizer is spending more than $11.6 billion to buy the remaining portion of migraine treatment maker Biohaven Pharmaceuticals it does not already own.

The New York drugmaker said Tuesday it will pay $148.50 in cash for each share of Biohaven, which makes Nurtec ODT for treating and preventing migraines and has another nasal spray under development.

The price represents a 33 percent premium over Biohaven’s 90-day weighted average trading price of $111.70 for Biohaven Pharmaceutical Holding Co. Ltd., which is based in New Haven, Connecticut.

Shares of Biohaven, which had tumble below $100 in recent weeks, soared 72 percent before the opening bell to about $72. Pfizer’s stock slipped.

Pfizer Inc. has been flush with cash in recent quarters, thanks in part to sales of its COVID-19 vaccine Comirnaty and now its pill treatment for the virus, Paxlovid.