Google's set to report fourth-quarter earnings after market close. The search giant will be keen to avoid a repeat of last quarter's gaffe, when it released its earnings early. It will also be hoping to finally deliver mobile success, driving real earnings growth.

As people increasingly turn to smartphones and tablets for their Internet needs, Google has had a difficult time trying to make money from advertising on mobile, so cost-per-click (CPC) is an important metric to watch. If Google's CPC looks like it's bottoming out, or even rising, then the company's mobile initiative is working.