SHANGHAI: Trading opened Friday on China's long-awaited Nasdaq-style board, ChiNext, with all 28 listed small- and medium-sized firms rocketing in early trade on fevered interest from investors.

Trading in several shares including Anhui Anke Biotechnology (Group) Ltd. was suspended after they tripped market circuit-breakers in place to curb rampant speculation.

Anhui Anke was the biggest gainer, up 160.59 percent from its initial public offering price of 17.00 yuan at 44.3.

Movie production house Huayi Brothers Media Corp. soared 130.93 percent from its IPO price of 28.58 yuan at 66.00.

The other stocks were up at least 45 percent in the first few minutes of trading.

The board, based in the southern boomtown of Shenzhen, is expected to give small- and medium-sized companies access to financing and encourage private equity firms and venture capitalists to back start-ups.

Regulators hope the new market will help fuel young companies and other firms with high-growth potential in the world's third-largest economy, following the example of Wall Street's Nasdaq.

But there have also been worries that the new board may divert funds from the main boards and drag down stock prices.

The first 28 companies to list on the board, ranging from software to medical equipment makers, raised about 16 billion yuan (2.3 billion dollars) in their IPOs -- more than double initial forecasts.

Shang Fulin, chairman of the China Securities Regulatory Commission, said at a launch ceremony last week that the opening of ChiNext was an "important step towards implementing the national strategy on promoting innovation".

But he also cautioned investors to trade on the new board in a "rational" way, recognising that start-up stocks have potential for strong growth but are also characterised by unstable financial results.

"The growth enterprise market faces relatively higher risks of irrational and speculative trading and market manipulation," he said.

The bourse on Friday reiterated trading rules -- if the prices move up or down 80 percent during the first day, trading will be suspended until the final three minutes of the session.

Two other debut-day circuit-breakers were in place, under which trading is suspended for 30 minutes if shares in a company move up or down 20 percent from the opening price, and then another 30 minutes for a 50-percent shift.

ChiNext has said the restrictions will help curb risks, maintain market stability and protect investors.

Despite the hype among Chinese investors, the second board was expected to have a limited impact on the Nasdaq, analysts said, with companies looking for exposure to global investors still likely to seek a US listing.

"For high-quality companies wanting to establish a global presence, I think they will still look at the Nasdaq because they will have more access to global capital," said Ren Xianfang, a Beijing-based economist at IHS Global Insight.