Chinese shares plunged Thursday, even as Beijing grasps for solutions to stem the selling, including relaxing rules on the use of borrowed funds to invest in stocks. That effort comes as a surprising turnaround given concerns that margin lending fueled a too-hot rally over the past year. The Shanghai Composite closed down 3.5% while the smaller Shenzhen market was down 5.6%. The ChiNext board, composed of small-cap stocks, sank 4%. Even after losing nearly a quarter of its value from a mid-June high, China’s main stock market has almost doubled in value over the past year. In the minutes before closing, China’s blue chips staged a minirally, which some analysts put down to buying from government-backed funds. Stocks in large, state-owned firms benefited most, with PetroChina Co. nearly hitting its daily upward limit of 10%, rising 8.8%, and China Petroleum & Chemical Corp., or Sinopec, up 5.5%. Just 60 […]