HONG KONG (MarketWatch) — As Chinese stocks took another sharp turn lower Wednesday, more listed companies rushed to halt trading in their shares, with more than 40% of the country’s stocks suspended by the time the session started, according to various media reports.

More than 1,200 listed Chinese companies had their stocks in trading halt by Wednesday, accounting for well above 40% of the entire pool of 2,808 issues, the Southern Metropolis Daily reported, citing data as of midnight Tuesday from cninfo.com, the market information site sanctioned by China’s securities regulator.

It marked the largest wave of trading halts in the history of China’s equity markets, the report said.

Many of the companies didn’t disclose the reasons behind their trading suspensions, though some cited the consideration of unspecified significant events, asset restructuring, or private share placements, according to various recent reports.

The Southern Metropolis report, as well as other recent commentary, said many of the halts were likely meant to protect the shares from the ongoing selloff in Chinese markets, although a previous Reuters report said that the companies would face fines if they were discovered to have requested trading suspensions without good reason.

In some cases, large shareholders who had pledged stocks as collateral may have also requested stock suspensions for the relevant names to prevent the risk of an account liquidation, the Southern Metropolis Daily said.

But with an ever-larger number of companies seeking to pull their stocks from active trade, the exchanges may begin refusing some requests, if only because they are “too busy to attend to all” of them, the newspaper quoted an unnamed source close to the Shenzhen Stock Exchange as saying.

By the midday break Wednesday, the Shanghai Composite Index SHCOMP, -0.63% had fallen 3.9%, moving off of an 8.2% loss earlier in the morning. For the week to date, it was down 2.8%, with a month-to-date loss of more than 16%. The plunge also dragged down the Hong Kong market, where many of the same Chinese companies also list, with the Hang Seng Index HSI, -2.06% down 4.3% late in the morning session.

The heavy losses came despite a rare pledge early Wednesday by the People’s Bank of China that it would closely monitor stock movements and continue to use various means to support the state-backed margin-finance entity — China Securities Finance Corp. (CSF) — in order to protect market stability.

The central bank’s statement marked the latest in a slate of measures in recent days to support the equity market, including the purchase of shares and the easing of margin-lending rules.