1. Global epidemic: Pfizer is one of the vaccine manufacturers in COVID-19. Due to many factors such as vaccine effect and supply, Pfizer's share price has been greatly affected.
2. Poor performance: Pfizer released a financial report in recent stock market transactions, showing that its revenue and net profit in the last quarter were not as good as expected, which may also lead to a decline in its share price.
3. Increased competitive pressure: Pfizer is not the only company in the health care industry, and there are many competitors, such as Merck and Johnson & Johnson. Fierce competition may also lead to a decline in share prices.