SAN JOSE, Calif. -

Internet giants are buying up businesses in the San Francisco Bay Area and across the country by the hundreds.
   
The San Jose Mercury News reports that since 2010, Google has purchased nearly 200 small companies - at a rate of more than one deal every week.
   
Last year, Google, Facebook, Twitter and Cisco Systems were among the nation's top five purchasers of privately held tech firms, typically startups.
   
The newspaper cites data that show overall, Bay Area businesses closed 329 such deals last year, far more than any other region.
   
Analysts tell the Mercury News these investments signal a fundamental change in Silicon Valley's culture of innovation. Facing intense competition, companies are supplementing research and development efforts by simply purchasing a potential rival that's already started or completed the work.