FDA approval of a new drug is a significant positive catalyst for pharmaceutical companies. It not only validates the company's research and development efforts but also opens up a new revenue stream. Given the specific approval for a treatment in a field with limited options, such as noncirrhotic NASH with moderate to advanced liver fibrosis, this approval could position Madrigal Pharmaceuticals as a leader in this niche market. The immediate positive reaction in stock price reflects investor optimism about the potential market size and revenue generation capabilities of Rezdiffra.