Xu Xiang, known in China as "Hedge Fund Brother No 1" and three managers from Citic Securities have been formally arrested on insider trading charges.

The arrests were reported by Xinhua News Agency on Friday.

Xu, head of Shanghai-based Zexi Investment Management, was detained on Nov 1 during investigations into stock trading after a market rout in which China's A-share market lost $5 trillion in value between June and August.