China™s stock-index futures tumbled after the nation™s securities regulator took measures to rein in margin trading at three of the nation™s biggest brokerages.

Futures on the CSI 300 Index expiring in February, the most active contract, slumped 5.7 percent to 3,474.80 as of 9:18 a.m. local time. The regulator suspended Citic Securities Co., Haitong Securities Co. and Guotai Junan Securities Co. from adding margin-finance and securities lending accounts for three months following rule violations.

The Shanghai Composite Index climbed 1.2 percent to 3,376.50 on Jan. 16. Hong Kong™s Hang Seng China Enterprises Index fell 0.9 percent to 12,076.74.

The Shanghai gauge advanced 2.8 percent last week, a 10th week of gains that™s the longest winning streak since May 2007, after credit growth expanded and speculation grew the central bank will cut reserve-requirement ratios.

The CSI 300 Index rose 0.9. The Hang Seng Index lost 1 percent. The Bloomberg China-US Equity Index, the measure of the most-traded U.S.-listed Chinese companies, added less than 0.1 percent in New York.

Source: Bloomberg