Google is starting to show signs of a technology company hitting middle age. The 14-year-old company, which went public in 2004, is starting to exhibit some dramatic signs of slowing down. It's getting harder for investors to consider the company a rapid-growth story, as its growth continues to decelerate.

Shares of the company were slammed 8% on Jan. 20, the day after it reported disappointing fourth-quarter results. But the search-engine company's slowdown in profit growth has been brewing for quite some time.

Google's slowdown in growth has been most apparent in the number that matters most to investors: earnings per share. The company's earnings per share grew 13.1% in 2011, down from 29% in 2010, and 53% in 2009, says S&P's Capital IQ. In 2006, the company's earnings per share rose 98%, which explains why it won so many fast friends on Wall Street.

On a quarterly basis, Google's financial slowdown is also apparent. Earnings per share in the fourth quarter grew 5.3%, down from 28% growth in the fourth quarter of 2010.

Google's management, during its conference call with investors, vowed to jump-start growth again. It claims that it's very early in finding ways to make more money from the Android operating system for smartphones. The company gives Android away for free to companies that make mobile computing devices.

But the looming risks are large. The company is in the process of integrating Motorola's cellphone business, which gets Google into the less-profitable hardware business. And Google's famed profit margins are already in decline. The company's return on investors' equity was 18.7% in 2011, down from 20.7% in 2010.

Meanwhile, last week, rival Facebook filed plans to go public. Facebook has been much more successful than Google in the area of social networking, which is increasingly popular with advertisers.

Google's transition is coming just as investors are...