????先是團購網站Groupon解雇了安德魯?梅森。現在流媒體音樂服務供應商Pandora又表示喬?肯尼迪即將離職。在那些上市首日股價飆升、并因此在公共市場引起轟動的公司擔任CEO，現在看起來真像是一場職業冒險。

????Pandora在2010年6月將股價定為16美元。首個交易日，它的股價猛漲至26美元，隨后一天又跌至發行價以下。去年，Pandora的股價曾一度跌至每股8美元，到昨天收盤時漲回到11.73美元。這個價位離首次公開募股的價格仍然低了27%，比歷史最高點低了55%。

????Groupon的股價軌跡與之相似，不過更加夸張。它的發行價為每股20美元，僅僅幾個小時后就上漲到31.14美元，隨之而來的便是緩慢而痛苦的下跌。梅森離開Groupon的那一天，公司股價已經低至每股4.24美元，比起首次公開募股價格低了79%，比首日轉瞬即逝的歷史最高點低了86%。

????看看這兩只股票。經驗豐富的投資者早已對第一個明顯的教訓諳熟于心：當心第一天的飛漲。很久以前，購買首日發行的股票，它的漲勢很可能會持續幾周，甚至幾個月。但是最近急躁的投資者對于快速變現短期收益或拋空短命股票已經越來越缺乏耐心。

????不過經過事后分析，還有一些事情也逐漸清楚：對許多公司而言，利用互聯網盈利似乎變得越來越難。能夠與消費者產生大量共鳴的商業模式無法轉化為帶來穩定收入增長的業務。

????在第一波網絡初創公司的浪潮中，亞馬遜（Amazon）和雅虎（Yahoo）這樣的公司在穩定盈利之前，早期都有過幾年的虧損。而更近一些嶄露頭角的公司，如谷歌（Google）和Facebook，已經能獲得20%至30%的利潤空間。

????不過這些都是例外。許多網絡公司最近的首次公開募股都在與稍縱即逝的盈利或常規性的季度虧損作斗爭。Pandora和Groupon的利潤空間與谷歌的對比如下圖所示。的確，谷歌是一家資歷更老、更加成熟的公司，但是它公開發售股票時，擁有13%的凈利潤空間和20%的稅前利潤率。

????First Groupon fired Andrew Mason. Now Pandora says Joe Kennedy is leaving Pandora. Being a CEO of a company that made a splash in the public markets with high-flying IPOs is starting to look like a job hazard.

????Pandora (P) priced its shares at $16 in June 2010. On its first day of trading, the stock shot up to $26 before plunging below its offering price the next day. After dipping as low as $8 a share last year, Pandora has rallied to $11.73 at yesterday's close. That's still 27% below its IPO price and 55% down from its record high.

????Groupon's (GRPN) stock has followed a similar if more extreme trajectory. Offered at $20 a share, the stock surged to $31.14 in a matter of hours, then began a slow painful slide. The day Mason left Groupon, the company's stock traded as low as $4.24 a share, a 79% discount from its offering price and 86% off its fleeting, first-day high.

????Looking at these two stocks, the first apparent lesson is one well-known to experienced investors: Beware the first-day pop. Once upon a time, buying a stock on the first day of trading could possibly let you in on a rally that could last months, if not weeks. But recently bearish investors have been impatient to cash in on quick gains or short stocks they believe have a brief shelf-life.

????But with more hindsight, something else is becoming clear: It seems to be getting harder for many companies to make money from the web. The business models that have resonated with consumers on a large scale simply aren't translating into businesses that can generate steady profit growth.

????In the first wave of Internet startups, companies like Amazon (AMZN) and Yahoo (YHOO) posted early losses for years before moving into steady profitability. Newer companies like Google (GOOG) and Facebook (FB) have emerged capable of delivering profit margins of 20% or 30%.

????But these are the exceptions. Many recent web IPOs have struggled with fleeting profits or regular quarterly losses. Compare the profit margins of Pandora and Groupon with that of Google in the chart below. Granted, Google is an older, more mature company, but when it went public it had net profit margin of 13% and a pretax margin of 20%.