* Alibaba's US IPO move could be a blow to Hong Kong stock exchange
* Analysts estimate Alibaba to be valued at least $140 bln
* Alibaba listing is the most anticipated deal since Facebook's IPO in 2012
* In talks with six banks for lead underwriting roles
By Elzio Barreto and Denny Thomas
HONG KONG, March 16 (Reuters) - Chinese e-commerce giant Alibaba Group Holding Ltd has decided to hold its long-awaited IPO in the United States and is in discussions with six banks to underwrite the deal, in what is set to the most high-profile public offering since Facebook Inc's listing nearly two years ago.
Alibaba said in a statement on Sunday it had decided to begin the U.S. IPO process, ending months of speculation about where it would go public.
Separately, sources told Reuters that Alibaba is in discussions with Citigroup, Credit Suisse, Deutsche Bank, Goldman Sachs Group, J.P. Morgan, and Morgan Stanley for lead underwriting roles.
Most of the six banks are to set to win the coveted role of joint global coordinator, added the sources, who were not authorised to discuss the matter publicly.
Analysts estimate the Hangzhou, China-based company has a value of at least $140 billion, and the IPO proceeds could exceed $15 billion, Reuters previously reported. The deal would be a huge coup for the six banks, as it would yield an estimated $260 million in underwriting fees, assuming 1.75 percent commission, and catapult them in league table rankings.
Alibaba declined to comment on the banks working on the deal. The banks mentioned in the report either declined comment or did not respond to Reuters' requests for a comment.
"This will be a huge deal, bigger than what people were anticipating," one person familiar with the process said, adding that the IPO was expected to be kicked off "very soon".
Reuters reported on Saturday that Alibaba is planning a U.S. IPO in the third quarter, with a filing of documents expected as early as April.
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Alibaba, whose platforms handle more goods than EBay Inc and Amazon.com Inc combined, was founded in 1999 by former English teacher Jack Ma and 17 other people. It has grown from a startup in Ma's apartment to a behemoth with offices around the world and more than 20,000 employees.
The listing will be closely watched by Alibaba's two largest shareholders - Yahoo Inc, which owns 24 percent, and Japan's Softbank Corp, which controls 37 percent. Alibaba's founders and some senior managers jointly own about 13 percent of the company.
Yahoo has said it plans to trim its stake in Alibaba through the IPO. It initially invested in Alibaba in 2005.