Why AstraZeneca Shares Slumped This Week Despite Positive Vaccine News

The news Monday regarding AstraZeneca (NYSE:AZN)'s trial of coronavirus vaccine AZD1222 seemed to be the type of information that would push a stock's price up, not down.

Interim results from the phase 1/2 trial of the company's vaccine, which was developed in partnership with Oxford University, suggested that it drove antibody and T-cell immune responses against COVID-19 in each of the study's 1,077 participants.