PFIZER ASTRAZENECA

PFIZER ASTRAZENECA

Chris Ratcliffe/Bloomberg

The Pfizer Inc. company logo is seen on packaging for Viagra tablets, produced by Pfizer Inc., in this arranged photograph taken in London, U.K., on Friday, May 2, 2014. AstraZeneca Plc rejected Pfizer Inc.'s sweetened takeover proposal, saying the 63.1 billion-pound ($106.5 billion) offer fails to recognize the value of the promising experimental medicines under development by the U.K.'s second-biggest drugmaker.