Three of China's biggest securities firms are under investigation in a fresh aftershock from this summer's market plunge.
Shares in Citic Securities Ltd. and Guosen Securities Ltd. fell Friday by the 10 percent daily limit after both said they were being probed by regulators. A third brokerage, Haitong Securities Ltd., issued a similar announcement after trading in its shares was suspended Friday morning. None gave details.
The Shanghai Composite Index closed down 5.5 percent.
Authorities have detained securities executives, an investment fund manager, government employees and a reporter for a business magazine following the collapse in prices that began in early...