Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

After reports indicated that Europe may be struggling more than some had previously expected and that it will take longer than many had hoped for the region to fully recover from the financial crisis, the major indexes are fighting back into positive territory today. As of 1:10 p.m. EST, the Dow Jones Industrial Average (DJINDICES:^DJI) is up a single point after dropping as much as 117 points earlier today. Both the S&P 500 and the NASDAQ have also risen from today's lows, sitting near breakeven.

This morning's drop would seem to be just another example of irrational behavior on Wall Street. In an attempt to educate investors on what such irrationality looks like, last week I began pointing out a few questionable price moves. It took just one week to prove my case.

Last week I noted that Orbitz Worldwide's (NYSE:OWW) 7.8% jump after Expedia (NASDAQ: EXPE) reported better-than-expected earnings was truly irrational. My warning to investors was that just because Expedia performed well during the third quarter didn't mean Orbitz would follow suit, and that buying shares of Orbitz prior to its own earnings release was a mistake.

Orbitz posted earnings today. Quarterly profit came in at $0.11 per share, while Wall Street was looking for $0.13. And although revenue was up 11% from the same quarter last year to $220.9 million, management now believes it will only report full-year sales of $840 million. That figure is the low end of the $840 million-$850 million management projected back in August and lower than the $849 million analysts were estimating. The weaker-than-expected results and lower estimates, combined with the irrational move the stock made last week, has now sent shares down more than 19% today.  

Orbitz isn't the only travel and leisure business struggling today. Shares of Host Hotels & Resorts (NYSE:HST) are down 1.5% after the company released third-quarter earnings this morning. The decline come despite higher room rates and occupancy, as funds from operations per share missed estimates by $0.01, despite rising from $0.17 per share in Q3 2012 to $0.25 in  the most recent reporting period. EPS in at $0.03, which beat the $0.05 loss reported in 2012 as revenue rose 5% from the same quarter last year. Lastly, the company said that its fourth quarter has been hurt by the October government shutdown and that it expects full-year adjusted funds from operations to fall within the range of $1.28-$1.30, which is down from $1.28-$1.32.  

Fool contributor Matt Thalman has no position in any stocks mentioned. Check back Monday through Friday as Matt explains what causing the big market movers of the day, and every Saturday for a weekly recap. Follow Matt on Twitter @mthalman5513

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