Facebook reported higher than expected quarterly revenue but its profit fell 9 percent as the social media company increased spending to boost mobile revenue and future growth. Expenses will grow 55 to 60 percent in 2015 from last year, including an 82 percent jump in the second quarter to $2.77 billion, it added.

"We're investing in the next set of services and what will be future investments like Messenger, WhatsApp and Oculus," Chief Operating Officer Sheryl Sandberg said on Wednesday after the earnings report. She was referring to Facebook's two messaging services and virtual reality headset maker Oculus Rift, whose first product for consumers has yet to be launched.

Messenger has more than 700 million users, and the app has been downloaded more than 1 billion times on Android, Google Inc's mobile operating system, Facebook said.

Over the coming months, Facebook will add new advertising formats to photo-sharing app Instagram, which was launched in Brazil, Germany and Japan in the second quarter, Sandberg added on a conference call.

Facebook continued to expand its reach, hitting 1.49 billion monthly active users as of June 30, up 13 percent from a year earlier. Of these, 1.31 billion accessed the service through mobile devices, a rise of 23 percent.

Daily active users increased to 968 million in June, up 17 percent from the same month last year.

For the quarter, revenue jumped to $4.04 billion from $2.91 billion.

Advertising revenue grew 43 percent to $3.83 billion. Mobile ads accounted for 76 percent of that, up from 62 percent in the same quarter last year. The average price paid per ad rose 220 percent while total ad impressions, a measure of the number of times an ad is viewed, fell 55 percent.