Newspapers invest $15 million more in Topix.net

News aggregator Topix.net on Monday announced that it has received an additional investment of $15 million from the three newspaper groups that already own a majority stake in the company.

After the latest funding, Gannett and Tribune each own 33.7 percent stakes, and McClatchy owns an 11.9 percent stake in Topix. Last year, Knight Ridder-- which was acquired by McClatchy in March--jointly purchased a 75 percent stake in Topix with Gannett and Tribune. The second round of funding boosts the newspaper companies' combined total stake to 79.3 percent.

"The support of these leading newspaper companies has been invaluable in helping us quadruple our traffic since their initial investment," Topix CEO Rich Skrenta said in a statement.

Topix, founded in 2002, aggregates news and categorizes it into topics. Earlier this year, the company added the ability for readers to comment on articles. Topix provides automated related links on some of the Web sites of newspapers owned by the investors and is adding reader comment capabilities to their sites as well.

Chris Tolles, vice president of sales and marketing at Topix, said the company would spend the funding on hiring and marketing. Company executives want to double the 25-person staff over the next year, he said. "For us to grow, we needed the money."

The Palo Alto, Calif.-based company, which was valued at $72 million earlier this year, has jumped from being among the top 45 news sites to among the top 25, per Hitwise statistics, according to Tolles.