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 printed circuit board manufacturer Multi-Fineline Electronix (Nasdaq: MFLX) were shorting out today, losing as much as 10% in intraday trading on heavier-than-average volume.

So what: Quarterly results don't happen in a vacuum. Investors get their hearts set on certain numbers and if a company doesn't deliver, then the stock typically gets taken to the woodshed. After yesterday's close, Multi-Fineline "updated" its guidance for its fiscal third quarter -- which, in this case, was a nice way of saying that it was lowering its numbers. For the quarter, management now sees revenue coming in at $191 million with a gross margin of 12%. Previously, it had told investors that it would see $200 million to $220 million in revenue with gross margins between 12% and 13%. Wall Street analysts were projecting $210 million on the top line.

Now what: Multi-Fineline CEO Reza Meshgin placed the blame for the miss on a "reduction in demand from one key customer" toward the end of June. Meshgin was optimistic otherwise and said that sales would increase sequentially in the fiscal fourth quarter. Investors with a longer time horizon may see this as a short-term blip and be patient enough to stick around and see if demand picks back up in the quarters ahead. Today's trading action, however, suggests that there are plenty of investors with itchy trigger fingers who are already off to look for greener pastures.

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Fool contributor Matt Koppenheffer does not have a financial interest in any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or Facebook. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.