'Facebook advertisers boost spending 10 fold'

Facebook’s biggest advertisers have boosted spending by at least 10-fold in the past year as the social network crossed the half-billion user mark, becoming more alluring to marketers that want to reach a broad online audience.

Some advertisers have increased spending by as much as 20-fold or more, Facebook COO Sheryl Sandberg said in an interview. The site’s ad prices have held steady even as user growth fuelled a surge in inventory, or pages that can carry ads, she said.

“Two years ago the big brands were experimenting with us,” said Sandberg, declining to identify which customers were spending more. “They started buying with us a year ago. Now, they’re going big.” As a closely held company, Facebook doesn’t disclose revenue figures.

Facebook is courting advertisers and ramping up the pace of acquisitions to wring profit from its more than 500 million users, who don’t pay to use the site. The owner of the world’s largest social network may put off an initial public offering until 2012 to give CEO Mark Zuckerberg more time to add sales and lure users, people familiar with the matter said last week.

The company plans to make more purchases to recruit leaders and build features to keep users glued to its pages.