On Tuesday morning, the Dow Jones Industrials (^DJI -1.52%) extended yesterday's post-holiday drop with a steeper decline of 104 points, to 16,920, as of 11 a.m. EDT. Investors remained nervous about the prospects for second-quarter earnings season and are also waiting to see what the Federal Reserve's latest meeting minutes (due tomorrow) will tell them about the future course of monetary policy. Among the worst performers on the day were Boeing (BA -2.22%) and American Express (AXP -0.93%), both of which are dealing with special challenges even as the broader market falls back.


Source: Boeing.

Boeing declined nearly 2% as it tries to address a couple difficult situations at the same time. Over the weekend, the aerospace giant had the bad fortune of having several fuselages for its top-selling 737 aircraft damaged when a train derailed in Montana, en route to Boeing's production facilities in western Washington. That news didn't send Boeing shares down yesterday, though, and it's yet unclear whether the accident will cause longer-term production issues. Perhaps more important, though, the company faces a key congressional vote on reauthorizing the Export-Import Bank, which provides credit to foreign companies buying U.S. products like Boeing aircraft. Without the bank's backing, Boeing would have to take on huge amounts of credit risk in order to keep doing business with buyers that currently take advantage of bank financing, and that could pose a true threat to the company's long-term growth.

American Express, meanwhile, fell 1.3%. The credit card giant's antitrust trial against the U.S. Department of Justice began yesterday, with the government alleging that American Express engaged in practices that reduced competition from rival networks charging lower fees for transaction processing. AmEx customers are expected to testify that they wanted to use tactics such as discounting in order to encourage greater competition among various cards, but that American Express rules kept them from doing so and therefore put them in a position where they couldn't negotiate lower costs from the card network. American Express believes that its rules actually helped merchants, and it also argues that its relatively small market share compared to other credit card network companies makes its influence insufficient to have any anti-competitive effect. With the trial expected to last for months, investors shouldn't look for any quick resolution on the litigation front.

Today's drop in the Dow Jones Industrials is nothing new for investors familiar with the index's buy-on-dips history of recent years. It's important not to overreact to a two-day drop that amounts to barely 1%, no matter how intimidating a triple-digit decline might seem.