If you use an investment firm with a broker you can look them up by name at the FINRA BrokerCheck website. FINRA regulates brokers. The BrokerCheck site will give details on the brokers registration and list any complaints or violations against them.
From the site :
"FINRA oversees the people and firms that sell stocks, bonds, mutual funds and other securities. Simply type in your current or prospective broker’s name to see employment history, certifications, and licenses—as well as regulatory actions, violations or complaints you might want to know about. You also can get information about your broker’s firm. There’s no reason not to check."