The market jumped on Monday after pharmaceutical giant Pfizer announced that, amid ongoing trials, its Covid-19 vaccine was 90% effective, and it rallied again on Friday. The S&P 500 was up 2.2% for the week, hitting an all-time high on Friday, while the Dow Jones Industrial Average ended the week up 4.1%. However, not all companies benefited from the news. Stocks of companies that have thrived during the pandemic, including Facebook, Amazon and Zoom, fell sharply this week.
