Google Inc., operator of the world’s largest Web-search engine, has passed Apple Inc. to become the most-owned stock by the 50 biggest actively managed U.S. mutual funds, according to a report by Citigroup Inc.

Among hedge funds, Google was also the top holding, according to the report, which examined investments at the end of the fourth quarter for the largest funds by asset size.

Google’s shares are now trading at about 25 times profit, compared with a price-to-earnings ratio of less than 10 for Apple, according to data compiled by Bloomberg. That gap is at its widest since June 2005, two years before competition between the two companies in mobile devices began to intensify.

Under Chief Executive Officer Larry Page, Google has extended a lead in Web search, boosting its share to 67 percent, and in smartphone software, where it commands 70 percent of the market. That helps the Mountain View, California-based company benefit from two big shifts -- the boom in tablets and smartphones away from traditional computers and the move toward digital advertising.

Apple, based in Cupertino, California, is undergoing slowing revenue growth and narrowing margins amid accelerating mobile competition led by Samsung Electronics Co. and other users of Google’s Android operating system. A year and a half after the death of co-founder Steve Jobs, Apple is working to release new products that can build on the successes of the iPod music player, the iPhone smartphone and the iPad tablet computer, which revolutionized their respective industries.