Google IPO | 10 Years Later

Google's best and worst acquisitions

Justin Solomon | CNBC

Google's C-suite has a lot of money, and it enjoys spending it.

Since its IPO 10 years ago, Google has spent at least $23 billion buying 145 companies, according to FactSet. Of all those deals, financial analysts say three stand out as clear winners.

The first is YouTube, which Google bought in 2006 for $1.65 billion. The price tag seemed high at the time, but YouTube has grown by leaps and bounds. The digital marketing firm eMarketer says YouTube raked in $5.6 billion in gross revenue last year alone.

Another success is Android. Andy Rubin sold his company to Google in 2005, and then helped develop the mobile operating system into the global powerhouse it is today. The operating system will run on 80 percent of the smartphones sold this year, according to IDC.

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"Google doesn't make any money on the operating system itself," said Neil Doshi of CRT Capital. "But, because it's tied to Google properties and services, they can really monetize well from Google searches and Gmail and all the other Google applications that come along with that."

A final winner analysts highlight is DoubleClick, which expanded Google's reach in online advertising into display ads. Google bought DoubleClick for $3.1 billion in 2007.

But what about the busts?

Analysts agree on three acquisitions that didn't work out: ITA Software, dMarc Broadcasting and Slide, a social app developer that Google shut down two years after buying the company for $182 million.

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Most memorable Google doodles

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Finally, there is the mixed bag of Motorola, which Google bought for more than $12 billion, and then sold for $3 billion two years later. However, Youssef Squali of Cantor Fitzgerald says Google did keep most of Motorola's portfolio of mobile patents, offering the company legal protection for its Android software.

Now the question for investors is what Google will buy next with its $61 billion cash pile. Analysts say the company could make a play in the social space given the underwhelming performance of Google Plus.

An acquisition in media is also a possibility. Aaron Kessler of Raymond James says Pandora could still be in Google's crosshairs.

(Scroll through an interactive timeline of Google's post-IPO history, below)

—By CNBC's Josh Lipton