Four United States-based law firms have initiated investigations against software giant Infosys, PTI reported on Saturday. Bronstein, Gewirtz & Grossman, Rosen Law Firm, Pomerantz Law Firm and Goldberg Law PC will examine potential claims by Infosys investors to find out if the company violated federal securities laws.

The development follows Vishal Sikka’s resignation as the firm’s chief executive officer and managing director on Friday. On Saturday, the company announced that its board of directors had approved a share buyback offer of up to Rs 13,000 crore, PTI reported.

In a press release, Rosen Law firm said it is “investigating potential securities claims on behalf of shareholders of Infosys Limited resulting from allegations that Infosys may have issued materially misleading business information to the investing public.” It said that it is preparing a class action lawsuit to recover investor losses.

Bronstein law firm said its investigation “concerns whether Infosys and [some] of its officers and/or directors have complied with federal securities laws.”