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 Aruba Networks (NASDAQ: ARUN) rose 21% Wednesday after Bloomberg reported that Hewlett-Packard (NYSE:HPQ) is in talks to acquire the networking products company.

So what: According to the report, which cited "people with knowledge of the matter," a deal could be announced as early as next week. HP could use the acquisition to bolster its own networking business, which falls under its enterprise group and generated revenue of $562 million in its most recent quarter. For reference, when Aruba Networks announces fiscal second-quarter 2015 results tomorrow, analysts expect it to report quarterly revenue of roughly $210 million.

Now what: Despite Aruba's $2.5 billion market cap as of this writing, I wouldn't be surprised if HP is indeed interested. CEO Meg Whitman first told investors last August that HP was in the position to consider growth by acquisition, then fulfilled that promise with the purchase of open source cloud software company Eucalyptus last quarter.

But these sorts of big acquisitions are never a sure thing. And even if it does happen, we still don't have any concrete information on the financial terms. For now, I wouldn't blame Aruba investors for taking at least some short-term profit off the table. At the very least, just be sure not to base your investment thesis for Aruba -- or any other company, for that matter -- on a possible acquisition.

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.