Yahoo CEO Marissa Mayer plans to spin off its remaining 15 percent stake in China's Alibaba's e-commerce operation into a new entity in her program to maximize shareholder value.

The scheme will result in a $16B tax investment on the $40B Alibaba stake.

The Alibaba holding represents about 85 percent of Yahoo's market value.

Mayer noted that Yahoo has already turned over nearly $10B in value to shareholder through share repurchases.

"This level of capital return is historic, especially for a company of our size," she said in a Jan. 27 statement. "The plan announced today vividly demonstrates our commitment to being good stewards of capital and increasing shareholder value."

The spin-off will be completed during the final quarter of the year.

Mayer also reported that Q4 net income dropped 52 percent to $170M on flat sales of $1.2B.

The CEO is buoyed by Yahoo's ability to "show stability in our core business."

She also noted that investment in mobile, video, native and social is positioning Yahoo to be a winner in "the future of advertising."