From boom to bust, China's Internet companies listed on the U.S. stock market have fallen to earth. Shares of Renren, Jiayuan and Netqin dropped below their offering prices just days after shining performances on their first day of trading.

Their slide suggests investors may have lost their taste for China's dot-com stocks. Is it a bubble?

Taking a look back, most Chinese internet stocks have been touted as the Chinese analogues to Western innovators such as Facebook, MySpace, Groupon and Twitter. In this way, they rebranded their companies to allure American investors. But in reality, their business models are just copies of Western firms.

Ahead of Renren's IPO, some American investor pointed out that the Chinese firm could hardly compare to Facebook in terms of user base and market share. They noted that Renren's offering price was unreasonably high given its financial fundamentals.

A story published in the latest edition of the Economist newspaper also warned American investors of the risk of buying internet stocks, especially those from China, as they face restrictions from Chinese law and policy.

Feng Po, an analyst at China Venture, cited Jianyuan as an example of an overvalued firm.

"The matchmaking Website is in fact small, doesn't have a new business model and lacks innovation," Feng said.

As investor exuberance cools, they have begun to think soberly about Chinese internet stocks and have come to understand what these companies really are, he added.

近来，在美上市的中国概念股股价表现不佳，新近上市的世纪佳缘、网秦、人人等公司均在短短几日内跌破IPO发行价。

是TMT互联网概念股集中扎堆上市后投资者产生了"审美疲劳"？还是中国概念股的确存在估值泡沫呢？

回顾美国上市的中国TMT互联网概念股，大多顶着"中国版XX"光环。此前市场大热的人人插上了"中国Facebook"，后来的世纪佳缘是"中国MySpace。在概念背后，其实质经营模式却存在老套模仿的弊端。

早在人人网上市之前，也有美国投资者指出，无论从用户数量还是市场份额，人人网和Facebook还不能相提并论，而二级市场的估值定价也早已偏离其真实财务数据。

最新一期的《经济学人》杂志更是指出，美国投资者忽视了互联网公司估值的风险性，尤其是对于中国互联网公司来说，除了市场竞争日趋激烈，中国互联网公司的发展还必须受到严格的法律法规和政策因素制约。

China Venture投中集团资本分析师冯坡表示，世纪佳缘就是一个例子。

其本身其实存在经营模式老旧，创新缺乏，公司规模较小等问题。

冯坡表示，如果说大热之后的泡沫破裂，主要因为美国投资者开始冷静判断，并开始通过各种渠道思考了解中国上市企业的真实状况。