NEW YORK (MarketWatch) — Shares of Yahoo YHOO, -2.93% surged 6.8% in after-hours trade Tuesday, after the Internet company disclosed plans on how to monetize the stake in still owns in Chinese e-commerce behemoth Alibaba BABA, -1.01% Yahoo also reported fourth-quarter earnings that topped expectations. Yahoo said it plans to spin off its 384-million-share stake in Alibaba into a separate, publicly-traded company named SpinCo. “Post-spin, using the closing price for Alibaba as of January 26, we will have returned nearly $ 50 billion dollars of value to our shareholders,” said Chief Executive Marissa Mayer. “This level of capital return is historic, especially for a company of our size.” Yahoo also said it would continue to hold its 35.5% interest in Yahoo Japan. Separately, reported fourth-quarter adjusted earnings of 30 cents a share, down from 46 cents a share in the year-earlier period, but above the FactSet consensus analyst estimate of 29 cents a share.