Investors are facing multibillion-dollar losses in the lightly regulated U.S. penny-stock market as pump-and-dump schemes proliferate, according to a Financial Times report citing market data and regulatory filings. The newspaper highlighted a wave of social-media promotions that drove up prices in several thinly traded companies before abrupt collapses. Last month, seven Nasdaq-listed Chinese issuers alone shed a combined $3.7 billion in market capitalization after such campaigns ended, the FT said. Regulators have repeatedly warned that micro-cap shares are especially vulnerable to manipulation because of their low liquidity and limited disclosure requirements, yet the number of suspected frauds is rising. The report underscores mounting concern that retail traders are being lured into speculative bets that crumble once early promoters cash out.