Final answer:
The U.S. government agency that monitors the stock market is called the Securities and Exchange Commission (SEC).
Step-by-step explanation:
The U.S. government agency that monitors the stock market is called the Securities and Exchange Commission (SEC). The SEC is an independent agency of the federal government that is responsible for protecting investors, maintaining fair and efficient markets, and facilitating capital formation. It regulates the stock market to ensure that companies disclose accurate and timely information to the public, and it also enforces laws against fraudulent activities in the securities market.