A wave of suspected “pump-and-dump” schemes has erased roughly $3.7 billion of market value from seven Nasdaq-listed Chinese micro-cap companies, according to data cited by the Financial Times. Concorde International, Ostin Technology, Top KingWin, Skyline Builders, Everbright Digital, Park Ha Biological Technology and Pheton Holdings each plunged more than 80 percent in July after surging sharply on the back of aggressive social-media promotion. Predictive-analytics firm InvestorLink said it detected clusters of coordinated posts on WhatsApp and Reddit urging retail investors to buy the shares weeks before the stocks collapsed. Pheton’s price slid 95 percent in a single session, while Ostin dropped 94 percent. InvestorLink said geolocation data linked some promotional accounts to Russia and Iran. The FBI reported a 300 percent year-on-year increase in complaints tied to so-called ramp-and-dump stock fraud, warning that scammers are impersonating legitimate brokers and analysts online. The SEC and Nasdaq declined to comment on the individual share moves. Market observers say the frauds have proliferated amid a record influx of Chinese companies into the US micro-cap market over the past two years, where thin liquidity and limited disclosure make share prices easier to manipulate.