Stocks surged for a second day on Friday, after regulators intensified their efforts to shore up the country's falling market.

The Shanghai Composite Index closed at 3,877.80, up 4.5 percent, after jumping as much as 6.7 percent, while the Shenzhen Component Index advanced 4.6 percent to 12,038.15.

About 1,300 stocks surged by the daily limit of 10 percent, led by brokerage, consumer staple, port and aerospace sectors. More than 1,300 companies remain suspended from trading.

Brokerage firms, including Guotai Junan, Everbright Securities, Guangfa Securities and Orient Securities, jumped 10 percent on Friday.

The rebound of the Shanghai index narrowed losses from its June 12 peak to 25 percent, after the central bank granted 120 billion yuan to China Securities Finance Corp, which provides margin financing loans to brokerages, according to Caixin.

The People's Bank of China will continue to support liquidity need, it said in a statement on Thursday, adding that the central bank has also granted the CSF to issue short-term bonds in the interbank market to replenish capital.

Among a spade of measures launched to stem the plunge, State-owned banks including Bank of China and Bank of Agriculture also vowed not to sell shares, while China Development Bank and Export-Import Bank pledged to invest more on the stock market through subsidiaries.

The move came as China Securities Regulatory Commission encouraged major shareholders and senior managers to steady stock prices by buying more shares.

The CSI 300 gauge rose 5.4 percent to 4,106.56.