Final answer:
The Glass-Steagall Act limited the activities a company could engage in if it owned a bank by prohibiting commercial banks from engaging in investment banking and creating the FDIC to insure personal bank deposits.
Step-by-step explanation:
The act that limited the activities a company could engage in if it owned a bank is the Glass-Steagall Act. This act was enacted in June 1933 and prohibited commercial banks from engaging in investment banking, which means they were not allowed to speculate in the stock market with deposits. Additionally, the Glass-Steagall Act created the Federal Deposit Insurance Corporation (FDIC), which insured personal bank deposits up to $2,500.