Early this year, Pfizer told investors it expected to sell $21.5 billion worth of its Covid-19 products in 2023. No one believed it. Shares of Pfizer (ticker: PFE) fell 37.3% between the start of the year and the market close on Friday, even as the company announced a $43 billion acquisition and a sizable list of major new product launches. Good news for Pfizer came and went, but investors just kept on selling, fixated on the decline of the company’s massive Covid-19 revenue. Then on Friday, after the market closed, Pfizer ratcheted down its guidance for this year, to a combined $12.5 billion from its Covid-19 vaccine and therapeutic. The announcement was a major acknowledgment Wall Street had been right, and the company wrong, about the future of the Covid-19 franchise. While questions remain about how the Covid-19 products will perform next year, and in the years that follow, Pfizer’s