下周五将是OpenTable上市两周年。上市两年来的大部分时间里，OpenTable是逐步复苏的IPO市场中一颗耀眼的明星。而且OpenTable的大部分承诺都得到了兑现——堪称新型网络公司典范，激活了资本市场的沉闷一角。

    OpenTable 2009年IPO标志着经济衰退之后互联网公司IPO的卷土重来。在OpenTable上市前两个季度，没有一家获风投支持的初创企业进行IPO。OpenTable的IPO不仅展现了对于一家成长的盈利互联网公司，市场是安全的，而且该股上市后的大飙也有暖场效应，有助于LinkedIn、Zillow等其他公司跟进。

    OpenTable是一宗包装漂亮的IPO，市场需要藉此让机构投资者相信，web2.0不仅是流行词引发的短暂的市场狂热。上个月，该股股价曾高至118.66美元，几乎是发行价20美元的近6倍。

    但上个月，围绕OpenTable的市场人气发生了变化，而且，这种转变可能反映了投资者对Facebook 等网络公司上市前高涨的估值日益不安。OpenTable的股价已较高点回落逾1/5，股票卖空额在上升，这说明看跌者正在赌股价进一步下跌。

    不过，这种下跌并不意外。1个月前，OpenTable股价的2011年动态市盈率达到了101倍。而回调将该股股价推低至2月初首次触及的水平——也就是说，两年期回报率仍令人艳羡。另一方面，该股股价2011年动态市盈率仍高达82倍。与之形成对比的是，谷歌(Google)的市盈率仅16倍。

    而且，卖空额(即预期股价下跌的卖空者持有的股份数)4月份升至570万股，两个月前为400万股。这相当于OpenTable自由流通股数量的27%，即每4股自由流通股就有超过1股由看跌者持有。

    OpenTable过去也曾面临高卖空额，但看涨者取得了胜利。本月早些时候，当OpenTable公布季度业绩和首席执行官杰夫•乔丹将卸任的消息时，这种状况发生了变化。

    加入OpenTable前曾供职eBay多年的乔丹将出任公司执行董事长，管理大权交由2005年以来担任公司首席财务官的马修•罗伯茨。人事变动出现于季度业绩强劲之时， OpenTable营收增长60%，每股收益28美分也比预期高出了5美分。

    即便乔丹在硅谷声名不错，首席执行官更替消息也不应令股价大跌。财务报告显示，1季度净利润率12%，与上年同期持平，但低于前一季的16%。一些分析师表示19%的营运利润率低于他们的预期。

    利润增长曾推动OpenTable的股价大涨。该公司的商业计划称不上有很大的创新。事实上，其成功显示了某些商业领域——如独立餐厅——的电子商务发展仍滞后。开拓这些电子商务领域的公司随着规模扩大，营收增速快于营运成本上升。但OpenTable的利润率至多也只是持平。在投资者希望看到利润率增长之时，一个优秀的首席执行官选择离开让OpenTable的股价上涨动力大减。一旦这种情况发生，悲观的卖空者介入，乐观者可能会输。

    要扭转股价下跌之势，OpenTable需要的是一个特别强劲的季度业绩。但股价回调提醒人们，不管OpenTable管理得有多好，都不能使其三位数的市盈率变得合理。如果悲观者和卖空者获胜，这家运营良好的高估值公司股价可能大跌，即便目前公司样样都好。

    而且，这可能进而打击投资者对其他希望参与火爆IPO市场的高估值网络公司的热情。

    Next Friday will mark OpenTable's second anniversary in the public markets. For most of its publicly traded two years, OpenTable (OPEN) has been an bright star in an IPO market struggling its way back to relevance. And for the most part, OpenTable has delivered on its promise -- a hearty example of the new breed of web companies who could enliven a lethargic corner of the capital markets.

    OpenTable's 2009 IPO marked the return of the Internet IPO in the wake of the recession. During the two quarters before OpenTable went public, no venture-backed startups staged an IPO. OpenTable showed that not only were the markets safe for a growing, profitable Internet company, but its surging stock price since then helped warm the waters for others like LinkedIn and Zillow to jump in.

    OpenTable was a gift-wrapped IPO, just what the market needed to seduce institutional investors into the notion that web2.0 isn't just a buzzword-turned-market-mania that given would time burn itself out. Last month, the stock traded as high as $118.66 a share, nearly six times its $20 offering price.

    But in the last month, the sentiment has changed around OpenTable. And that shift may reflect a growing sense of unease in the inflated valuations of web companies like Facebook as they head for the public markets. OpenTable's stock has lost more than a fifth of its peak value, and short interest on the stock is rising, suggesting bearish investors are betting on further declines to come.

    On the one hand, the decline isn't surprising. OpenTable's stock was trading at 101 times its estimated 2011 earnings a month ago. And the correction brought the stock back down to levels it first reached in early February -- that is, to returns still enviable for a two-year period. On the other hand, the stock is still trading at 82 times its 2011 earnings. Google (GOOG), by contrast, is trading at 16 times earnings.

    And short interest, shares held by short sellers in expectation of a decline, rose to 5.7 million shares at the end of April from 4 million shares two months earlier. That's equal to 27% of OpenTable's stock float, which means that more than 1 in 4 OpenTable shares available for trading is held by someone expecting the stock to decline.

    OpenTable has faced a high short interest before, but the enthusiasm of its bullish investors always prevailed. That changed earlier this month, when OpenTable announced its quarterly earnings as well as the news that its CEO Jeff Jordan would step down.

    Jordan, an eBay (EBAY) veteran before joining OpenTable, will become its executive chairman, handing the reins to Matthew Roberts, its CFO since 2005. The news came in the midst of what on the surface seemed a strong financial quarter, with OpenTable's revenue rising 60% and the 28-cents-a-share earnings coming in five cents stronger than estimates.

    As good as Jordan's name is in Silicon Valley, news of the change in CEOs shouldn't have caused the stock to plunge. The financial report also showed its net profit margin at 12% in the first quarter, flat with the year-ago figure but down from 16% in the previous quarter. Some analysts thought the 19% operating margins was lower than they expected.

    Profit growth had powered OpenTable's stock rally. The company's business plan wasn't radically innovative. Rather, its success showed that there are corners of the business world -- like independent restaurants -- that haven't yet been adequately been brought online. And that companies that mine these untapped areas of e-commerce can, as they scale up, grow revenue faster than operating costs.But OpenTable's profits are remaining flat at best. Seeing a valued CEO depart at the moment when investors are hoping to see margins grow took some wind out of OpenTable's power rally. Once that happened, the bearish short sellers stepped in, and the bulls couldn't overpower them this time.

    All OpenTable needs is an exceptionally strong quarter to reverse the stock decline. But the correction is a reminder that OpenTable, no matter how well it's managed, can't justify a triple-digit P/E ratio. If bears and short sellers win out, the company may go from a well run business that is overvalued to a company that is seeing its stock plummeting even though it's doing everything right.

    And that in turn could dampen the market's enthusiasm for the other highly-valued web stocks that want a piece of the hot IPO market.