San Francisco (AFP) - Yahoo formally notified US regulators that it is spinning off its stake in Chinese e-commerce giant Alibaba to an independent new company called Aabaco Holdings.Aabaco will wind up owning approximately 384 million shares of Alibaba Group, representing an interest of about 15 percent, according to a filing with the US Securities and Exchange Commission.The move was designed to sidestep taxes and appease investors eager to tap into Yahoo's multi-billion-dollar stake in Alibaba. It is also seen as a chance for Yahoo CEO Marissa Mayer to show she can lead the company to renewed glory.Yahoo was awaiting a ruling by the US Internal Revenue Service about what portion of the transaction will be tax-free.