Yahoo has completed its 1.1 billion US dollar (£710 million) acquisition of online blogging forum Tumblr.
The move represents Yahoo chief executive Marissa Mayer's boldest move since she left Google a little less than a year ago to lead Yahoo's comeback.
It also marks Yahoo's most expensive acquisition since the California-based company bought online search engine Overture for 1.3 billion US dollars (£839 million) 10 years ago.
Ms Mayer is betting that Tumblr, a six-year-old service started by high school dropout David Karp, will help Yahoo bring in more traffic and advertisers on smartphones and tablets.
Under the terms originally announced in May, Tumblr will remain independently operated and Mr Karp will stay as chief executive officer.
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