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 financial workflow software specialist Advent Software (NYSE: ADVS) got a bum deal today, falling as much as 16.1% on a sudden spike of heavy trading.

So what: Advent shares were sent slowly southward by a decent but unimpressive second-quarter report last night, but the big hit happened just after lunchtime today, Eastern time. My sources don't show any additional news or analyst downgrades to explain the sudden move, but there's some evidence of heavy hitters selling shares without much regard for the market-moving consequences.

Now what: According to the Nasdaq's trade reports, this stock tends to shift in nice little 100-share lots but all that changed for one minute at 1:03 p.m. ET. Several lots involving thousands of shares traded hands at lower and lower prices -- and then it was all over except for counting the percentage drops. It's a miniature "flash crash" on a much smaller scale than the one affecting much larger companies like Procter & Gamble (NYSE: PG) and Accenture (NYSE: ACN) last year. Advent is an easily manipulated small cap, though somewhat more insulated from trading shenanigans than true micro caps, thanks to a solid $5 million daily trading volume. Still, not quite big enough to be safe even with the trading stops that were put in place to avoid another flash crash.

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Fool contributor Anders Bylund holds no position in any of the companies discussed here. Motley Fool newsletter services have recommended buying shares of Accenture and Procter & Gamble. 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 is investors writing for investors.