Alibaba chairman Jack Ma and vice chairman Joseph Tsai are planning to raise more than $US2 billion ($2.85 billion) through a margin loan pledged against the company's stock, according to people familiar with the matter.

The money raised may be used to fund Blue Pool Capital, the family office of Alibaba set up by Tsai, two of the people said, asking not to be named as details aren't public. Credit Suisse, Goldman Sachs  and Morgan Stanley are among banks working on the transaction, they said.

The loan may be announced as early as this month, after a lockup period on stock owned by Ma and Tsai expires on September 21, one of the people said. No final decision has been made and the deal may still fall through, they said.

Both men are billionaires with considerable stakes in Alibaba, which creates a challenge in broadening their personal holdings without panicking Alibaba investors, said Gil Luria, an analyst at Wedbush Securities in Los Angeles.

"Since Mr Tsai said publicly on the last earnings call that he and Mr Ma will not be selling shares at the lockup expiration, this may be their best way for diversifying their personal portfolio without breaking a promise," Luria said.

In a margin loan, a borrower secures a loan by pledging an asset, and typically agrees to hand over cash to the lender if the value of the collateral declines. The lender can usually sell some of the collateral if the borrower is unable to post cash. Banks are keen to do these deals because of the lucrative fees.

Ma has a net worth of $US29.4 billion and Tsai of $US4.3 billion, according to the Bloomberg Billionaires Index.

"Share financing is very common for founders and senior executives who hold such a strong belief in the future growth potential of their companies," Jim Wilkinson, a spokesman for Alibaba, said Thursday. "This is prudent financial planning and management."

Representatives for Credit Suisse and Goldman Sachs declined to comment. Officials at Morgan Stanley didn't respond to requests for comment.

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