(Bloomberg) -- China is expanding its net stock selling ban from major mutual funds to some insurers, another sign that authorities are trying to support the slumping stock market, said people familiar with the matter.

Regulators issued the so-called window guidance to at least two state-owned insurance firms on Monday, telling them to refrain from selling more onshore shares than they purchased, according to the people, who asked not to be identified discussing private information. 

This is the first time that these firms have received such guidance, which was commonly given last year but usually only to large mutual funds, the people said. Another top insurer said it got the instructions in early January, one of the people added. 

Shanghai Stock Exchange didn’t immediately reply to a fax seeking comment.

The move came as Chinese authorities consider a package of measures to shore up the stock market. Policy makers are seeking to mobilize about 2 trillion yuan ($279 billion), mainly from the offshore accounts of state-owned enterprises, as part of a stabilization fund to buy shares onshore through the Hong Kong exchange link, Bloomberg reported Tuesday. 

Premier Li Qiang called for more rigorous and effective measures to stabilize the market on Monday, after the benchmark CSI 300 Index fell to a five-year low. Stocks have been hammered by factors ranging from the nation’s property crisis to rising geopolitical tensions and fears of a deflationary spiral in the world’s second-largest economy.

©2024 Bloomberg L.P.