Successful investors don't act hurriedly on the basis of a headline number. Judging by the market's reaction to yesterday's earnings release from Nasdaq OMX (NYSE:NDAQ), some of the exchange operator's shareholders have forgotten this rule in the current crisis. Selling the shares down 12% yesterday -- and down another 5% as of this writing today -- they are giving patient investors an excellent opportunity to own this franchise at an attractive price.

Don't forget the EPS adjustment
Yes, GAAP-diluted earnings decreased by nearly 90% year over year to $0.24 per share. However, last year's comparable quarter included a massive $431 million gain on the sale of Nasdaq's London Stock Exchange stake. Strip that and a few other items out, and you get a very different picture: Adjusted earnings per share increased 28% to $0.52.

More importantly, matched market share in NYSE securities is up, to 23%, and the integration of OMX is ahead of schedule. The target for achieving $100 million in cost savings from the merger has been moved up -- again -- to the current quarter. The original target was the fourth quarter of 2009!

Net U.S. cash equity trading revenue has also risen, by a smart 31%. Some of the Nasdaq's large- and mid-cap stocks that have jumped the most in trading volume over the past year include Microsoft (NASDAQ:MSFT), ImClone Systems (NASDAQ:IMCL), Electronic Arts (NASDAQ:ERTS), the PowerShares QQQ ETF (NASDAQ:QQQQ) and ... Nasdaq OMX itself.

Exchanges look cheap, and Nasdaq is no exception
When I covered NYSE Euronext's (NYSE:NYX) earnings last week, I concluded that the shares looked attractive. At less than 13 times the lowest estimate of 2009 EPS of $2.17, I can do no less for Nasdaq OMX's stock today.

Under Bob Greifeld's leadership, the company is making steady progress toward ambitious goals. The stock's path won't be even, but now is a good time for investors to hitch a ride with this smart operator.

More Foolishness:

Fool contributor Alex Dumortier, CFA, has a beneficial interest in Microsoft, but in none of the other companies mentioned in this article. He recommended Nasdaq OMX in the May 2007 issue of  Motley Fool Inside Value, where it remains a selection, along with Microsoft. NYSE Euronext is a Rule Breakers pick. Electronic Arts is a Stock Advisor choice. Try any of our Foolish newsletter services free for 30 days. The Motley Fool has a disclosure policy.