Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes – just in case they're material to our investing thesis.

What: Shares of Comtech Telecommunications (Nasdaq: CMTL) are down 11% on the day after the company reported better than expected first-quarter results but disappointed investors by lowering future sales expectations.

So what: Comtech Telecommunications actually reported a very solid quarter that easily blew past analyst expectations in large part because expenses fell by a third. Comtech also benefited from a one-time $12.5 million payment from CPI International (Nasdaq: CPII) after their merger was canceled in September. On the flip side, Comtech warned that future revenues would fall due to lower demand from the U.S. Army for its amplifiers and communications products.

Now what: Investing in the stock market is about looking forward, not dwelling on the past. Although Comtech provided investors with a stellar quarter, if you dig a bit deeper, the numbers aren't as impressive as they might seem. Comtech's expenses fell because it anticipated the drop in demand from their largest customer, the U.S. Army, and planned accordingly to keep costs in line. Comtech also didn't provide an exact number by which it expects revenue to decline, which could be another reason for today's fall. Leaving Wall Street in the dark about your revenue generation stream is generally not going to bode well for a company's stock price. Comtech pays out a tempting dividend, but with the overhang of a demand decline from its largest customer, I'd avoid this whole situation until we get some concrete expectations.

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Fool contributor Sean Williams does not own shares in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.