In the blink of an eye, human resources concern 51jobs ( JOBS) went from hot to very cold, as the China-based company warned fourth-quarter earnings would disappoint. The company said Tuesday that slow sales in December would contribute to "weaker" fourth-quarter revenue. The company provides recruitment services mainly in China. In early trading, the company's stock fell $16.75, or 38%, to $27.07. It was the Nasdaq's biggest percentage loser. Last year, the initial public offering for 51jobs was one of the hottest on Wall Street, up over 155%. China-based IPOs were some of the market's biggest movers last year. The company expects fourth-quarter revenue of 117 million to 121 million yuan, or $14.62 million, compared with a previous forecast range whose low end was 140 million yuan. "Sales in the latter part of December were lower than we expected. We do not believe that there has been any change to the competitive landscape or the state of the Chinese economy," said Rick Yan, the company's president and chief executive.