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 network-based telephony expert Broadsoft (Nasdaq: BSFT) lost signal today, falling as much as 15.4% on above-average trading volume.

So what: No news on Broadsoft itself today. IT markets are under general pressure from Oracle's (Nasdaq: ORCL) disappointing earnings report, but VoIP rivals Sonus Networks (Nasdaq: SONS) and Acme Packet (Nasdaq: APKT) are just trading in line with the Nasdaq drop, so it's not a sector effect. This smells like a major shareholder moving out of the stock and not caring if the move tramples smaller investors.

Now what: 'Tis the season for mutual fund rebalancing, and Broadsoft is a large holding in many funds. Lots of the largest fund management investors here are virtual unknowns, increasing the likelihood of bad trading policies somewhere in the mix. I fully expect this stock to bounce back in a matter of days as the market attempts to stay (or become) efficient.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.