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 Dutch business-card and pamphlet printer Vistaprint (Nasdaq: VPRT) are running out of red ink today, after falling as much as 38% on stupendously heavy volume.

So what: Revenue in the fourth quarter grew 27% year over year to $209 million, and non-GAAP earnings jumped 13% to $0.43 per share, roughly in line with Wall Street estimates. But guidance for next year pointed to shrinking earnings despite sharply higher sales targets, pouring buckets of ice water over the stock.

Now what: Less than five months ago, Vistaprint's growth plans impressed even the most hardened of analysts. Fellow Fool Rich Smith is more enthusiastic about rivals like Staples (Nasdaq: SPLS) and FedEx (NYSE: FDX), or even much-maligned office supply vendors OfficeMax (NYSE: OMX) and Office Depot (NYSE: ODP). And now, those brilliant growth ambitions are gone with the wind, like a business card dropped on the streets of Chicago. 

However, this Rule Breaker has lost more than 30% of its value overnight before, as recently as last year, and it came back from that abyss to crush the market in subsequent quarters. Rich is looking very smart today, but let's just say I'm not ready to sell Vistaprint short just yet.

Interested in more info on Vistaprint? Add it to your watchlist.