AstraZeneca Stock Slips as $2 Billion Summit Stake Deepens Oncology

AstraZeneca NYSE:AZN, the oncology and biopharmaceutical company, agreed to invest $2 billion in Summit Therapeutics to test new cancer drug combinations. Its shares were down about 0.7% at $164.95 at 9.55am EST time on Tuesday. That is a sizable commitment, but AstraZeneca is buying a stake, not t…