SAN FRANCISCO — Disgruntled investors have filed at least 14 securities suits against Facebook Inc. in federal courts since the social network’s lackluster initial public offering on May 17.

And general counsel Theodore Ullyot’s former firm, Kirkland & Ellis, is getting at least some of the work generated by the litigation. San Francisco litigation partners James Basile, head of the firm’s litigation practice, and Elizabeth Deeley filed a notice of appearance Tuesday on behalf of the company in one of the four securities suits filed in the Northern District. They’re the first lawyers to file appearances in any of the suits filed in federal court.