Yahoo Inc. is in talks to acquire a controlling stake in Dailymotion, one of the world's most popular online video websites, in what would be Yahoo CEO Marissa Mayer's largest deal since taking the reins in July, the Wall Street Journal reported on Tuesday.

Yahoo could purchase as much as 75 percent of Dailymotion, which is owned by French telecommunications firm France Telecom-Orange, according to the newspaper report, which cited anonymous sources.

Dailymotion could be valued at roughly $300 million, according to the report, which noted that the deal isn't imminent and could still fall apart.

Yahoo, Dailymotion and France-Telecom Orange declined to comment.

Dailymotion is the No. 12 ranked online video Web property in the world, according to industry research firm comScore, with 116 million unique monthly visitors and more than 2 billion videos viewed. Google Inc, which owns YouTube, is the world's No. 1 Web video property while Yahoo's various websites ranked 10th on the list.

The transaction for Dailymotion would represent Yahoo's largest deal since Mayer, a former Google executive, took charge last year. Yahoo has acquired several small mobile and Web start-up companies since Mayer became chief executive last year.