The logo of Alibaba Group is seen inside the company's headquarters in Hangzhou, Zhejiang province early November 11, 2014. [Photo/Agencies]

Alibaba Group Holding Ltd will buy back as much as $4 billion of stock as it tries to revive a share price battered by concerns about the slowing Chinese economy less than a year after going public.

The e-commerce operator will buy the shares over a two-year period, mainly to offset dilutions such as from its compensation programs. Wednesday's announcement came as the company posted first-quarter sales that rose at the slowest pace in at least three years and posted transaction volumes that missed estimates. Shares fell more than 6 percent in pre-market trading.

Alibaba's plunge in market value of about $100 billion, a decline bigger than Goldman Sachs Group Inc since November has been driven by a Chinese economy expanding at the weakest rate since 1990 and lawsuits concerning sales of counterfeit goods.

The company's revenue in the three months ended June rose 28 percent to 20.2 billion yuan ($3.2 billion), down from an average of 56 percent in the previous 12 quarters.

Gross merchandise volume, which measures transactions on its Chinese retail marketplaces, rose 34 percent to 673 billion yuan in the quarter, short of the 38 percent growth expected by analysts.

Alibaba is being squeezed by price cuts and competition in China's bigger cities, a shift to shopping on smartphones that generates less advertising revenue and the country's slowest economic growth since 1990.

That has not dulled billionaire Chairman Jack Ma's appetite for expansion. On Monday, he announced a $4.6 billion investment in Suning Commerce Group Co to get more access to the electronics retailer's network amid intensifying competition from online shopping site JD.com Inc.

"Online shopping in larger cities in China has already reached saturation," Li Muzhi, a Hong Kong-based analyst at Arete Research Service LLP, said by phone before the earnings. "Alibaba is also providing heavy discounts on its group-buying site to win market share."

Alibaba brought in former Goldman Sachs Group Inc partner Michael Evans this month to help its global push in August.

Ma is trying to diversify Alibaba's businesses while simultaneously tapping more of the 594 million Chinese who access the Internet from their smartphones and tablets.

The strategy includes expansion into entertainment, healthcare, location-based services pushing its own YunOS smartphone operating system.