All 28 stocks on ChiNext, China's new Nasdaq-style market for small and medium-sized companies, had been temporarily suspended within the first two hours of trading on its opening day Friday.

The stocks on the ChiNext exchange in Shenzhen, Guangdong Province, had all been suspended at least once by 11:20 a.m. under rules to prevent wild fluctuations in share prices.

To reduce speculation, the Shenzhen Stock Exchange issued special suspension rules if any stocks fluctuate too wildly on the first day of trading on ChiNext.

Under the rules, if any stock fluctuates beyond 20 percent from its opening price, it will be suspended for 30 minutes; if a stock fluctuates again beyond 50 percent of its opening price, it will be suspended for 30 minutes; and if a stock fluctuates more than 80 percent from its opening price, it will be suspended until 2:57 p.m., three minutes before daily trading ends.

All stocks reported rises from their IPO prices after trading began at 9:30 a.m. Friday.

Five stocks soared more than 200 percent from their IPO prices in the morning session on Friday. Zhongyuan Huadian Co. Ltd. increased the least by 119.08 percent from its IPO price.

ChiNext is aimed at providing fund-raising channels for small and medium-sized high technology businesses with high growth.

The central bank and the financial system would continue to support ChiNext, said Zhou Xiaochuan, governor of the People's Bank of China, the central bank, at the opening ceremony.

IPO launches in China have often seen steep price hikes followed by even steeper falls as investors snapped up quick profits.

At the opening of ChiNext at 9:30 a.m., film production firm Huayi Brothers Media Corp. was the biggest winner, more than doubling by 122.74 percent from its IPO price, to open at 63.66 yuan per share.

Zhongyuan Huadian Co. Ltd. increased the least by 46.26 percent from its IPO price to open at 47 yuan per share.

In the mainboard, Chinese shares rose more than 2 percent in the morning session.

The benchmark Shanghai Composite Index was up 2.13 percent to close at 3,023.46. The Shenzhen Component Index climbed 2.37 percent to 12,482.08 in the morning session.

Shares opened higher Friday, with the benchmark Shanghai Composite Index up 1.58 percent to open at 3,007.25. The Shenzhen Component Index rose 1.92 percent to open at 12,427.1.