Despite all the talk of tainted pet food and lead-laden toys, this year’s biggest export to America from communist 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% 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 America, of which 24 were from China. (Four other Chinese companies went public in America in mid-December 2006.) The firm said 152 American companies have gone public this year. “Being listed in the U.S. 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 U.S. and lure American investors, Mr. 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% and 263%. Star performers include JA Solar Holdings (up 263%), Yingli Green Energy Holding Co. (up 190%), and China Architectural Engineering (up 152%).

Of course, past performance isn’t an indicator of future prospects. “U.S. investors need to pay much attention to the risks that the Chinese market commands, such as financial infrastructure” and accounting, Mr. Lu said. Also, he said, most of the U.S.-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 China’s government “is much more hands-on than those in the U.S. 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%, went public this year above underwriters’ initial hopes. Among all other IPOs — both foreign and domestic — only 21%, or 37 companies, exceeded underwriters’ estimates.

Only two Chinese companies, or 8%, went public at a discount, while among all other IPOs, 28%, or 48 companies, had to accept discounts. Two Chinese companies matched underwriters’ predictions, while 89, or 51%, of other IPOs went public at the predicted price.

The fourth quarter is usually a strong one for IPOs, and there is a good chance that more Chinese companies will be trading on the NYSE and Nasdaq this year. It is difficult to predict the precise number because it can take many months for a company to go public after filing its official IPO application.

However, if there is sufficient demand, public offerings can occur with lighting speed. In early November, a pair of Chinese companies — the farm products maker Agria and the air travel advertising firm AirMedia Group — started trading within three weeks of filing IPO applications. Whether the China IPO trend can continue depends on the strength of the Chinese economy and the appetite of American investors. One factor that might discourage China’s companies from going public in America is the cost. Mr. Lu said it costs three to four times more for an IPO listing on New York Stock Exchange than on China’s Shenzhen Exchange for small and mid-size companies. The regulatory requirements under the Sarbanes-Oxley law, as well as the fees for legal, accounting, and financial consulting contribute to the higher expenses. “If homegrown exchanges in Asia become more reputable,” Mr. Stiller added, “Chinese firms may be less inclined to pursue IPOs in the U.S.”