San Francisco — Google more than tripled spending on acquisitions in the first half of the year to US$4.2 billion (S$5.2 billion), as the Internet company ramps up investments to expand its services.

The world’s largest online advertiser spent US$3.2 billion for thermostat firm Nest Labs in February and an extra US$1 billion on other purchases in the first half of the year, the California-based Web company said in a filing on Friday. That is up from US$1.3 billion for the same period a year ago, a previous filing showed.

The 2014 numbers exclude the more than US$1 billion Google has announced it is paying for home-camera company DropCam and satellite service Skybox Imaging — those deals did not close in the first half of the year.

Google’s scale of deal spending is climbing, as it works to bolster its core search-advertising business and extend its reach into new markets such as mobile, telecommunications and driverless cars.

The firm’s smaller acquisitions this year have covered everything from drones to video advertising.

“These acquisitions generally enhance the breadth and depth of our expertise in engineering and other functional areas, our technologies and product offerings,” said the firm in yesterday’s filing.

Google added that an antitrust investigation into its business practices by the Texas Attorney General’s office had ended. The attorney general’s office started a probe into the company in July 2010 to look into whether it was thwarting competition. The state had sought information from the firm, including the search engine’s formula for setting advertising rates.

The investigation’s end follows the US Federal Trade Commission’s dropping of a similar probe last year. The European Union Antitrust commissioner Joaquin Almunia in February also made a deal to resolve a row over how Google uses its market leadership to deal with competitors. Under the plan, the firm pledged to display results from rival search services. The agreement has since come under criticism.

Google spokesman Tim Drinan declined to comment on the ending of the Texas investigation. Bloomberg