AstraZeneca To Buy MedImmune

U.K.-based AstraZeneca PLC (AZN) offered $15.6 billion to buy Maryland-based MedImmune Inc. (MEDI). Shares of MedImmune leaped $8.56 to close at $56.57 while AstraZeneca stock tumbled $3.13 to close at $55.91.