TOKYO - SoftBank Group Corp on Wednesday said it will book an estimated gain of 4.6 trillion yen ($34.08 billion) on settling prepaid forward contracts using shares in Alibaba Group Holding, reducing its stake to 14.6% from 23.7%.

The estimate includes gains from the revaluation of shares in the Chinese e-commerce giant and derivative gains, SoftBank said in a filing.

The transaction "will be able to eliminate concerns about future cash outflows, and furthermore, reduce costs associated with these prepaid forward contracts," SoftBank said.

($1 = 134.9700 yen)

(Reporting by Sam Nussey; editing by Andrew Heavens and Jason Neely)