Embattled Chinese firm Longtop Financial Technologies (LFT.NYSE) has been sued by an investor claiming that the firm overstated profits and deliberately covered up weaknesses, Bloomberg reported. The suit, filed by Joe Mikus, seeks compensation for shareholders who suffered losses when reports emerged that the firm had doctored its financial statements, sending its share price tumbling 33% on April 26. Deloitte resigned as the firm’s auditor this week, and the US Securities and Exchange Commission (SEC) launched a probe. Longtop went public in 2007, with an IPO underwritten by Goldman Sachs (GS.NYSE) and Deutsche Bank (DB.NYSE, DBK.FWB). The case comes against a background of increasing scrutiny of US-listed Chinese firms, including an official SEC investigation of reverse takeovers made by mainland companies.