Investors dumped shares of Google after yesterday's fourth-quarter earnings call, sending shares of the company plummeting 9 percent in after-hours trading spurred largely in part by a reported 8 percent drop in cost per click (CPC), or the amount advertisers pay every time a person clicks one of Google's online ads.

Profits and total revenues were also lower. Google reported a 7 percent year-over-year increase in profits and overall revenues jumped 25 percent year-over-year. That's down from a 26 percent rise in profits and 33 percent increase in revenues in the previous quarter.

Susan Wojcicki, the company's senior vice president of ads, partially attributed the drop in CPC to foreign exchange rates but added that a host of factors influence the company's aggregate quarterly numbers.

Michael Graham, analyst for Cannacord Genuity, believes Google missed expectations almost entirely on currency dynamics, with a much smaller impact from unfavorable traffic mix. "While results were disappointing, these issues should pass, and underlying growth-predicting metrics were strong," Graham wrote in research notes.

Traffic mix seemed to be the theme among analysts, many of whom noted that more mobile ad clicks, which cost less than desktop clicks, could be a contributing factor to the company's falling CPC.

On the mobile side, Google CEO Larry Page called Android performance "quite simply, mind-boggling." Page said 700,000 phones are being activated per day, with 250 million Android devices in users' hands, up 50 million since November.

"In just two days over the holiday weekend, 3.7 million Androids were activated," Page said during a webcast of the earnings call posted to Google's website. "And today, we're announcing over 11 billion downloads from Android markets."

In the Q&A, Page said Google is in the early stages of monetization for a number of the company's new products, and Android happens to be one of those. "We've seen a lot of potential for us to make money on Android, and I think you'll see us increase that a lot over time," he said, declining to offer further details.

Page reiterated the company's intention to keep Motorola Mobility at arm's length once Google's offer to acquire that business is approved. 

"We've been very clear that Motorola's obviously going to remain a licensee of Android, and Android will remain open, and when we announced the deal, we really said our strategy is working with different manufacturers on lead devices is going to continue."

Shares of Google were trading at $589 this morning, almost 8 percent below Thursday's close.