SoftBank Corp. on Saturday forecast a gain of about ¥500 billion ($4.6 billion) from Alibaba Group Holding Ltd.'s listing a day earlier on the New York Stock Exchange.

As the biggest shareholder in the Chinese e-commerce Goliath, SoftBank announced in a statement it plans to book the gain in the six-month period ending Sept. 30.

Alibaba became one of the most valuable companies traded on Wall Street after its shares surged a staggering 38 percent to $93.89 apiece in the company's initial public offering.

SoftBank will have a 32.4 percent stake in Alibaba after the IPO, according to the prospectus.

Alibaba's listing on NYSE is a step toward global expansion, Masayoshi Son, chairman and CEO of SoftBank, said Friday told Bloomberg Television.

SoftBank said it will announce the precise size of the gain once it is verified. The windfall was generated by the issuance of new Alibaba shares and the conversion of convertible shares into ordinary stock as the listing took place, according to the telecoms giant.