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's happening: Shares of LivePerson (LPSN -0.80%) fell as much as 10.1% on Monday.

Why it's happening: Sometimes, stocks move for no obvious reason. That's what's happening to LivePerson today.

The operator of live assistance and expert advice did not file any SEC documents over the weekend, nor any press releases. Analysts haven't changed their opinion on the stock. Social media feeds are silent on this company and stock today. And no, the service itself didn't crash, thus sending investors running for the exits.

Stocks sometimes dip when investors look back at heavy gains and decide to take some profit off the table, but LivePerson shares are actually trading near multiyear lows.

Finally, you might expect that one of LivePerson's chief rivals might have launched some new threat to the company's core business. To the best of my knowledge, that isn't the case -- and an event like that would have shown up in social media discussions and news articles.

So there really isn't anything happening to LivePerson today. Yet, the stock took a 10% dive on heavy volume, kicked off by several very large trading blocks right after Monday's opening bell.

A large shareholder may have decided to unload some LivePerson shares this morning, for reasons unknown. These things happen, and can move market prices when there's a thinly traded small-cap stock involved. LivePerson fits that description to a T.