Pfizer shares gain $8 billion in a single day

Pfizer shares rose 2.4% on Tuesday, marking their fourth consecutive daily gain, adding more than $8 billion to the company’s market value in four days.

These gains came after the U.S. Food and Drug Administration issued new regulatory guidance regarding future COVID-19 vaccines.

The agency set stricter standards for approving future COVID-19 vaccines, with the expectation that new clinical trials demonstrate that the vaccines remain safe and effective before they can be approved for adults and children.

Separately, the company announced a $6 billion deal to develop and market a Chinese cancer drug, which will be acquired by 3SBIO, the drug’s developer.