Shares in Anglo-Swedish drugmaker AstraZeneca jumped 12.2% to close at $77.01 a share Monday after U.S. pharmaceutical firm Pfizer said it offered to buy the company for around $100 billion.

The Medicines Company will collaborate with AstraZeneca to help sell Brilinta (ticagrelor), AstraZeneca's struggling oral antiplatelet drug. The collaboration is the first stage of "a global ...