China's securities regulator restricts big share sales as stocks nose dive

China's stock regulator said Thursday it will curb major shareholders from selling more than 1% of total shares outstanding within three months, after markets closed early when the circuit-breaker mechanism was triggered for a second day this week.

The China Securities Regulatory Commission has ruled that large shareholders -- those holding 5% or more of shares in listed companies -- won't be allowed to sell more than 1% of total shares outstanding within the next three months, according to a statement on the regulator's website.

The agency also ruled that large shareholders must disclose their share reduction plans to the exchanges 15 trading sessions in advance.

The new measures came before the six-month share reduction ban on large shareholders is set to expire Friday. The new rules are aimed at "preventing concentrated share reduction" and "stabilizing market expectations," the statement said.

The CSRC prevented large shareholders from selling stakes for six months from July 8, 2015 in an attempt to arrest a stock-market meltdown.

Thursday's announcement came after Chinese stock markets closed at around 10:00 a.m. local time (0200 GMT) after the circuit breaker was triggered twice in the morning session.