The Federal Trade Commission on Tuesday opened an investigation into data brokers, the companies that collect and sell information about consumers for marketing and other purposes.

The agency issued administrative subpoenas to nine information resellers, requiring each company to provide extensive details about how it collects information about consumers; how it uses, stores, analyzes, and shares that data; and whether the company allows consumers to access and correct the records the company holds about them. Some of the companies named in the inquiry do not directly sell information about consumers, but offer analytics services in which they categorize, score, or evaluate consumer data.