By Michael Liedtke, Technology Writer

SAN FRANCISCO (AP) --

Yahoo is still limping along as the Internet company prepares to shed the financial crutch that has been propping up its stock during the three-year reign of CEO Marissa Mayer.

The latest evidence of the challenges facing Mayer emerged Tuesday with the release of Yahoo's second-quarter earnings report. Yahoo posted a nearly $22 million loss driving by soaring ad commission paid to its partners, while its net revenue remained unchanged from the previous year at $1.04 billion.

If not for the costs of employee stock compensation and one-time accounting items, Yahoo said it would have earned 16 cents per share. That figure was 2 cents per share below the average estimate among analysts polled by Zacks.

Yahoo's stock fell 55 cents, or 1.4 percent, to $39.18 in extended trading after the numbers came out.

Investors focus on Yahoo's net revenue because it reflects how much money the company keeps after paying its ad commissions, also known as "traffic acquisition costs." Yahoo has been dogged by a lack of net revenue growth since 2008, and the pattern has persisted since Mayer's arrival in July 2012.

Even though the volume of Internet advertising has been steadily rising during that stretch, Yahoo's revenue has been backpedaling while rivals such as Google Inc. and Facebook Inc. have been sprinting further ahead in the race for Web surfers' attention and marketing dollars. For instance, Google's net revenue climbed by 13 percent in the second quarter, while analysts' anticipate Facebook will report a 37 percent increase in revenue when it discloses its results next week.

Mayer has been promising to engineer a turnaround since Yahoo Inc. hired her away from Google, but only has made grudging progress so far. Yahoo's net revenue now has decreased or been unchanged from the previous year in eight of the previous 10 quarters. The Sunnyvale, California, company predicted its net revenue will decline once again in the current quarter ending in September.

Despite that funk, Yahoo's stock has more than doubled under Mayer's leadership, though the gain has had little to do with her strategy. Investors latch on to Yahoo primarily because it has owned a large stake in one of China's hottest Internet companies, e-commerce specialist, Alibaba Group.

Pressured by shareholders, Yahoo earlier this year filed plans to spin off its remaining 384 million Alibaba shares into a separate company that will be called Aabaco. Yahoo is still awaiting approval from the Internal Revenue Service to do the split on a tax-free basis, something that the company expects to receive before the end of the year.

Yahoo's Alibaba stake is currently worth nearly $32 billion, representing most of Yahoo's market value.

Without the Alibaba stock in its investment portfolio, Yahoo will probably have to start boosting its revenue or Mayer may face more shareholder unrest.

The nagging doubts about Yahoo's growth prospects have led to its stock dropping by more than 20 percent this year.

Mayer said Tuesday she remains confident Yahoo's net revenue will begin climbing again as the company reaps the benefits from its recent emphasis on mobile applications, advertising and search.

"Yahoo's transformation is well underway and overall I am very pleased with our progress," Mayer said.

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