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 Nokia (NOK -0.84%) soared 30% today after software giant Microsoft (MSFT -0.39%) agreed to acquire its handset business for about $7.2 billion in cash.

So what: Nokia and Microsoft have been struggling to gain traction in the smartphone space since forging a partnership in 2011, but today's deal should help the cause by allowing Microsoft to have total control over how the handset devices work with its Windows Phone software. Unfortunately, it also means that Microsoft is clearly trying to take on mobile computing gorillas Apple and Google, a fight that Wall Street isn't exactly confident that Microsoft can win.

Now what: Microsoft hopes to close the deal early next year. "Today marks a moment of reinvention," Microsoft CEO Steve Ballmer and Nokia CEO Stephen Elop said jointly. "With the commitment and resources of Microsoft to take Nokia's devices forward, we can now realize the full potential of the Windows ecosystem." The deal is also fueling speculation that Elop will emerge as the best candidate to succeed Ballmer, so the story is certainly worth paying attention to.