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 Chinese travel services specialist Ctrip.com International (Nasdaq: CTRP) took a detour today, falling as much as 17.4% on enormous trading volume.

So what: The company reported third-quarter results over the weekend with strong earnings and revenues but a disappointing sales outlook for the coming quarter. Analyst firm Brean Murray Carret then downgraded Ctrip to hold, citing multiple points of pressure on profit margins.

Now what: Shares of direct rival eLong (Nasdaq: LONG), which reports earnings after tonight's closing bell, jumped 8% on Ctrip's misery. Ctrip CEO Min Fan said that his company "continued to outperform the industry" this quarter, but eLong investors clearly don't think so. Tonight, we'll see whether eLong can beat Ctrip's sales growth of 20% year over year or 17% from the previous quarter.

Interested in more info about Ctrip.com? Click here to add it to My Watchlist.