Most of the time, earnings season goes pretty smoothly. But today's market action gave us all a reminder of what happens when things go very wrong. With the bungling of Google's (GOOGL 1.42%) premature earnings release, investors paid attention not just to the search giant's results, but to the channels of disseminating information between companies, regulators, and the general public. Google's mishap sent the Nasdaq down more than 1%, but the Dow Jones Industrials (^DJI 0.67%) managed to recover from a slightly steeper sell-off, to finish down just eight points on the session.

American Express (AXP 0.85%) led the Dow's decliners with a drop of about 3%, after reporting slower growth in customer spending than it had shown in previous years. As Fool contributor Amanda Alix noted earlier today, AmEx faces not just slower spending from its high-wealth personal clients, but also tight budgets for corporate accounts that drive a substantial amount of its overall revenue.

IBM (IBM 0.18%) also fell the better part of 3%, after an equally disappointing earnings report. Revenue declined substantially, with currency effects explaining only part of the decline. But Fool contributor Anders Bylund still believes in IBM, in part because it's holding up reasonably well in a sluggish global economy, and partly because it's still got a big leg up on the competition.

Finally, Microsoft (MSFT 0.46%) lost only a third of a percent during the regular session, but quickly fell more than 2.5% further during the first hour of after-hours trading. Like so many other tech companies, Microsoft suffered from the decline in overall PC sales, with revenue plunging 8%, and net profit down 22%, both worse numbers than expected. Still, with Windows 8 due to launch later this month, investors will soon forget about this release if the new operating system does well.