Brokers are people in the business of selling stock to investors. They are generally different from "Dealers," who buy and sell stock for themselves, though "Broker-Dealers" do both.
To do background research on a broker .
(a) Search the FINRA BrokerCheck database [Caveat: The data may go back only to 2007] and/or call the BrokerCheck Hotline (800-289-9999);
(b) Search a good news database for articles (for database suggestions, see the "News - Newspapers & Magazines - Articles" entry in this Guide);
(c) Get the broker's Form BD, "Uniform Application for Broker-Dealer Registration," by sending a request to the SEC at firstname.lastname@example.org. [Note: You can buy Form BDs filed with the SEC from 1979 through 2000 faster by calling ThomsonReuters Custom Research Services (formerly Disclosure) at 301-545-4930 (direct to D.C.) or 800-638-8241 (the toll-free main number)];
(d) Search for arbitration awards using the databases discussed in the Awards section of the "Arbitration, Mediation and Alternative Dispute Resolution" entry in this Guide.
(e) Search the internet with a good search engine to see if anything comes up.
(f) Search the National Futures Association's BASIC database.
(g) Search a database of SEC filings to see if anything comes up (see the Filings section of the "Securities and Exchange Commission" in this Guide).
(h) Call the appropriate state agency (in New York it's the Investor Protection Bureau, 212-416-8222).
Futures Brokers: Futures brokers are regulated by the National Futures Association, rather than the SEC. You can check for disciplinary actions through the National Futures Association's Background Affiliation Status Information Center. For more information, check out the NFA Web site.
Investment Advisers: If the broker is also an investment adviser, or works for an investment advisery firm, see also the entry for "Investment Advisers."