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 (NASDAQ:OSTK) were overachieving again today, climbing as much as 20% after the company posted a blockbuster earnings report.

So what: It was a strong report across the board as the online retailer delivered adjusted earnings per share of $0.15, up from $0.02 a year ago, and better than expectations of $0.12. Revenue, meanwhile, grew 22% to $293.2 million, well ahead of estimates at $277.2 million, as the main driver of the added revenue was a 21% increase in average order size. Gross margin was also up 170 basis points to 19.7% due to a shift in sales mix to higher-margin home and garden products and decreased warehousing costs.

Now what: Today's report was the company's sixth in a row to show positive EPS, a consistency it had previously been unable to achieve. With today's gain, shares are now up more than 400% in the past year, but are priced dearly at a P/E of 40. Online retail may be a fast-growing field, but industry leader has proven its willingness to bleed rivals dry time and again. I'm also concerned that nearly all the sales gains came from an increase in order value rather than new customers, as the latter is preferable and a better indicator of long-term growth. With analysts only expecting 8% revenue growth next year, today's jump may mark a good time to sell.

Fool contributor Jeremy Bowman has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. 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 has a disclosure policy.