SAN FRANCISCO (AP) - Twitter's losses are mounting as the messaging service struggles to expand its audience under recently hired CEO Jack Dorsey.

SAN FRANCISCO (AP) Twitter's losses are mounting as the messaging service struggles to expand its audience under recently hired CEO Jack Dorsey.

The challenges facing Dorsey came into sharper focus in a third-quarter report released Tuesday. The numbers covered the three months ending in September, a stretch when Dorsey was serving as interim CEO before Twitter hired him on a permanent basis.

Twitter ended the period with a core audience of 307 million active users, an increase of just 3 million from June. That wasn't much better than a gain of 2 million users in the previous quarter, a letdown that led to the departure of Twitter's previous CEO, Dick Costolo.

Revenue climbed 58 percent from last year to $569 million.

Twitter still lost $132 million, extending the company's uninterrupted history of losses since Dorsey co-founded the service nearly a decade ago. The San Francisco company has now accumulated losses of about $2 billion.

The evidence of Twitter's ongoing malaise reversed a recent rally in Twitter's stock, which came as investors grew optimistic that things would rapidly improve under Dorsey's leadership.

Twitter's stock plunged $4.07, or 13 percent, to $27.27 in extended trading after the report came out.

Although it remains among the Internet's most popular and influential means of communications, Twitter has seen its user growth slow down since its initial public offering of stock two years ago. Facebook and other rival services have been faring far better over that time.

Dorsey has vowed to come up new ways to make Twitter more appealing and easier to use for people who have been turned off by the service's chronological presentation of posts and sometimes-confusing quirks, such as its reliance on hashtags.

Twitter recently rolled out one of its biggest changes in years with a new channel that bundles video, photos and links to news stories to make it easier for people to find. The new feature, called Moments, was developed while Costolo was still CEO.

Dorsey also has signaled his resolve to make Twitter profitable by laying off 336 employees, or 8 percent of the company's workforce, earlier this month.