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: Sometimes, events cause a company's name to take on a meaning that's probably ... well, that's probably a bit different from what the corporate founders had intended to imply. That's the case with Innospec (Nasdaq: IOSP) today, whose shares are looking increasingly speculative as they crater 10% on no news at all.

So what: Today's sell-off looks like a photo negative of the unexplained run-up in share price that we saw back in March. Back then, fellow Fool Brian Pacampara suggested it was a rise in oil prices that had investors piling into Innospec as a "fuel efficiency play." Logically, CME Group's (NYSE: CME) decision to tighten margin requirements on the NYMEX could be causing a "pin-action" drop at Innospec, responding to fears this will cause oil prices to drop.

Now what: Maybe that's the right call, maybe not. Here's what I do know: A few months back, I took a cue from Berkshire Hathaway's (NYSE: BRK-A) (NYSE: BRK-B) purchase of Lubrizol (NYSE: LZ), and tapped Innospec as a cheap way for small investors to ride Buffett's coattails. So far that's been good advice, as Innospec shares rallied strongly in response to the deal.

Today, though, I look at Innospec and see a company that while arguably undervalued on a P/E basis, isn't generating the kind of free cash flow I'd need to see before buying it. Whether you join in the Innospec sell-off, or decide to ride it out, my advice is simply this: For heaven's sake, don't buy more. Not until the company gets its cash-generating machine back in working order.

Want to learn more about Innospec? Add it to your watchlist.

Berkshire Hathaway is a Motley Fool Inside Value recommendation and a Motley Fool Stock Advisor pick. The Fool owns shares of Berkshire Hathaway, but Fool contributor Rich Smith does not own shares of, nor is he short, any company named above.  The Motley Fool has a disclosure policy. Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.