Marissa Mayer

Marissa Mayer likely extended her life as Yahoo's CEO by spinning off the company's stake in Alibaba. The next challenge will be acting fast enough to fix the company's core business.

After months of anticipation, Yahoo announced late Tuesday it would spin off its massive stake in China's Alibaba Group directly to shareholders in a tax-free transaction. The stake, worth about $40 per Yahoo share, accounts for the bulk of the company's valuation, and investors including activist Starboard Value have recently pressured the company to divest it.