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 Orbitz Worldwide (NYSE: OWW) skyrocketed 22% Thursday after the online travel service announced it had agreed to be acquired by Expedia (NASDAQ:EXPE) for $12 per share in cash.

So what: That's a premium of roughly 29% over Orbitz's average share price for the five days leading into yesterday's close, and places the company's enterprise value at roughly $1.6 billion. The boards of both companies have approved the transaction, which still needs the approval of their respective shareholders. 

Orbitz also released fourth-quarter results today. Quarterly revenue grew 12% year over year to $221 million, which translated to a 20% increase in earnings per diluted share to $0.06. Analysts, on average, had expected earnings of $0.07 per share on sales of $220.1 million.

Now what: "Our mission at Orbitz Worldwide has been to build our brands to be the world's most rewarding places to plan and purchase travel," Orbitz CEO Barney Harford said in a press release. "We're excited for Orbitz Worldwide to join the Expedia, family and for our teams to work together to further enhance the offerings we provide to our customers and partners."

It appears Expedia is paying a slight premium for Orbitz given its modest growth, with shares of the latter trading after the pop at about 30 times this year's expected earnings. But by combining forces, both companies will be able to better compete with fast-growing competitors such as TripAdvisor, shares of which which also rose today following it's own solid fourth-quarter results and upbeat plans for 2015.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.