Despite all the talk of lead-laden toys, this year's biggest export to the United States from China may be initial public offerings.

The number of new Chinese companies listed this year on the New York Stock Exchange and on Nasdaq is expanding at a record pace, with Chinese companies comprising 12 percent of all IPOs and outnumbering the combined total of all other foreign IPOs, according to Renaissance Capital.

As of Friday, Greenwich, Conn-based Renaissance said 46 foreign companies had gone public in the US, of which 24 were from China. Four other Chinese companies went public in the US in mid-December 2006.

The firm said 152 US companies have gone public this year. "Being listed in the US market offers a strong boost to the brand recognition of the company," the China-based lead stock analyst for the independent financial research firm Morningstar, Lun Lu, said.

The appreciation of the Chinese yuan versus the dollar, China's large population, and the growing middle class all play a role in Chinese companies' push to be traded in the US and lure US investors, Lu said.

The most popular Chinese IPOs have been Internet, solar energy, online gambling, biotechnology, and telecommunications companies. So far, 15 of these companies were trading above their offering price as of Friday, including seven whose shares are up between 75 percent and 263 percent.

Star performers include JA Solar Holdings (up 263 percent), Yingli Green Energy Holding Co (up 190 percent), and China Architectural Engineering (up 152 percent).

Of course, past performance isn't an indicator of future prospects. "US investors need to pay much attention to the risks that the Chinese market commands, such as financial infrastructure" and accounting, Lu said.

Also, he said, most of the US-listed companies from China are small. "It is harder to evaluate a new firm with a short history," he said.

One source of comfort for investors in Chinese companies is that once they are listed in America, the companies must follow American accounting rules, "which eliminates worries about accounting errors." a research analyst at Renaissance, Philip Stiller, said.

Investors should remain alert because the Chinese government "is much more hands-on than those in the US and Europe," he said. "Swift changes in regulations could materially change the outlooks for certain firms."

The speed at which some of these Chinese companies' stocks are soaring is reminding some investors of the fact that the price of a new stock does not always reflect a company's fundamentals, but could be born of emotion and a day-trading mentality.

One means of assessing an IPO's potential is to compare the actual offering price with the price originally suggested by underwriters, experienced IPO watchers say.

If the IPO price matches or beats the underwriter's initial price range, it suggests savvy investors have a strong view of a company's products and finances. If underwriters cut their price to attract support, investors believe a company has a higher risk. Biotechnology companies, for example, often have gone public at discounts to underwriters' initial proposals.

Chinese companies, at least this year, in a number of cases have surpassed the underwriters' estimates. Twenty of them, or 83 percent, went public this year above underwriters' initial hopes. Among all other IPOs -- both foreign and domestic — only 21 percent, or 37 companies, exceeded underwriters' estimates.