Two Internet-based Chinese companies swept the U.S. IPO market Wednesday, with online television site Youku.com Inc. turning in the best performance since China's Baidu.com Inc.'s 2005 debut, and online bookseller E-Commerce China Dangdang Inc. ranking as the third best in 2010.

Youku.com and Dangdang dominate their respective businesses, with each claiming the top market share for their online niches. The pair have generated revenue increases throughout the global economic downturn in a country that has the largest number of Internet users in the world but a relatively low penetration rate, leaving lots of room to grow as more people there.