SUNNYVALE, United States — Yahoo! Inc.'s Marissa Mayer can't rely on Alibaba Group Holding Ltd. to bail her out much longer, putting the onus on her to accelerate a sales rebound that's only getting started.

Alibaba yesterday posted a 66 percent sales surge and more than doubled its net income for the last quarter of 2013, showing a reacceleration of growth ahead of a potential U.S. initial public offering. The results helped send shares of Yahoo, which owns about 24 percent of the Chinese e-commerce company, soaring in extended trading as the Web portal also reported its first sales growth in more than a year.

While the developments were positive, Mayer, who became Yahoo’s chief executive officer in mid-2012, will soon lose much of Alibaba’s assistance. After the Chinese company goes public, investors who bought Yahoo’s shares as a proxy for Alibaba can directly purchase stock of the e-commerce provider. That means Mayer must push a turnaround in Yahoo’s core online-advertising businesses in order to gain the same investor accolades.

“They’re still in the early stages of turning the business around,” said Colin Gillis, an analyst at BGC Partners, who has the equivalent of a hold rating on the shares. “It’s been struggling to find growth.”

No Growth

Yahoo said in a statement yesterday that its first-quarter sales, excluding revenue passed onto partner sites, were $1.09 billion, up from $1.07 billion a year earlier, in a sign that some of Mayer’s efforts to lure advertisers may be paying off. That compared with analysts’ average estimate of $1.08 billion, according to data compiled by Bloomberg. While revenue growth totaled less than 2 percent, the company’s sales had been flat or in decline since the last quarter of 2012.

Net income for the Sunnyvale, California-based company was $311.6 million, down from $390.3 million a year earlier, partly due to restructuring charges. Profit, minus items such as stock- based compensation, was 38 cents a share, while analysts had projected 37 cents a share.

In one sign that Mayer is confident some growth will continue, Yahoo projected second-quarter revenue of $1.06 billion to $1.1 billion. That was in line with analysts’ average estimate of $1.08 billion and could be higher than the $1.07 billion that the company generated a year earlier.

Moving Forward

Mayer said on a conference call that Yahoo has moved beyond sales decreases into a positive growth phase. She also acknowledged there is more work to do.

“We believe we have moved from our core business being in decline to a point of stable to modest growth,” she said. “Our modest success this quarter is an important start.”

Yahoo shares rose as much as 10 percent to as high as $37.70 in extended trading yesterday. The stock is down 15 percent so far this year.

Sales increased in the first quarter as Yahoo’s major advertising services expanded, the company said. Display revenue, which includes graphical ads on the home page, rose 2 percent, while search-based marketing sales jumped 9 percent. The company also continues to pour money into the business.

Total operating expenses rose 16 percent to $1.1 billion during the quarter.

Alibaba Factor

Yahoo, which bought a stake in Alibaba in 2005, has long relied on the Chinese e-commerce company for a boost. Alibaba’s 66 percent sales jump for the final quarter of 2013 is up from 51 percent in the previous period.

“The Alibaba numbers were very, very strong,” said Brian Wieser, an analyst at Pivotal Research Group, who has the equivalent of a hold rating on the stock. “It’s certainly a very strong positive for Alibaba -- and for Yahoo.”

Yahoo is set to sell about 40 percent of its stake in Alibaba at the time of the company’s IPO and then can unload more shares in the future.

Optimism around Alibaba’s valuation helped spur an upgrade of Yahoo’s stock yesterday by Ben Schachter, an analyst at Macquarie Securities USA Inc. The Chinese company could be valued at $160 billion to $180 billion at its IPO, he wrote in a note in which he raised Yahoo’s rating to the equivalent of a buy from a neutral after the shares pulled back recently.

“This is clearly a trading call not, in any way, a positive call on Yahoo’s core fundamentals,” Schachter wrote, putting the company’s price target at $40.

Long Turnaround

Mayer has said that a turnaround of Yahoo will take years, a point she repeated on the conference call yesterday.

“We believe that the type of growth we’d like to see will take multiple years,” she said.

To spur new growth, the CEO, after redesigning the company’s services, is adding more professional content to woo users. That’s included hiring high-profile journalists and executives.

Earlier this month, Yahoo said it would add a leading name in cosmetics, Bobbi Brown, to be its editor-in-chief of beauty coverage. Katie Couric recently joined to bolster Yahoo’s video efforts and former New York Times columnist David Pogue came aboard to lead technology coverage.

More professional content could be on the way. Yahoo is considering adding high-quality, longer-form video shows that would have multiple episodes, according to people with knowledge of the matter. That would come after striking deals to show other premium content, such as past episodes of “Saturday Night Live,” and backing some shorter-form programs, including Tom Hanks’s animated series “Electric City.”

Mayer said during the call that there would be a bigger focus on premium content for it video services. The spending should be in line with past years’ expenditures, she said.

In addition to video, another focus area for the company is mobile. Yahoo said yesterday that it gets about 430 million users from mobile devices, making up more than half its audience.

The efforts come as Yahoo improves its tools for advertising on its services. That includes a feature to help clients better target audiences and an advertising exchange that gives advertisers more tools to manage promotions.

By Brian Womack; Editors: Pui-Wing Tam, Ben Livesey.