WASHINGTON — Stepping into a volatile debate in the technology sector, the Federal Trade Commission on Friday said it would use its subpoena power to begin an investigation of so-called patent trolls, businesses whose primary purpose is to stockpile patents and use them to sue other companies.

The action, which the commission’s chairwoman recommended in June, is the first step in what is likely to be a lengthy and broad investigation. It could eventually result in antitrust enforcement against some of the companies and could provide momentum for efforts under way in Congress to tighten restrictions on such lawsuits.

The effort is intended to document the costs and benefits of a rising tide of patent litigation, said Edith Ramirez, the commission’s chairwoman. In announcing the investigation, the F.T.C. said it would seek information from roughly 25 companies that buy and sell patents, and 15 other companies that manufacture devices and write software and applications.

“Patents are key to innovation and competition, so it’s important for us to get a better understanding” of how the companies, also known as patent assertion entities, operate, Ms. Ramirez said on Friday.