Alibaba f-1 filing with frameAlibaba, China’s e-commerce giant, filed paperwork today (read it here) to publicly offer stock in the U.S., a move that will likely attract many billions of dollars in investor capital and also finally let owners of Yahoo stock know how much that company’s 24% stake in the company is actually worth. Alibaba is considered the world’s largest e-commerce site, both online and on mobile, operating a series of marketplaces — all for third-party partners that run their own online stores there. The company also runs, AliExpress and provides cloud-computing services. Its closest U.S. analog is Amazon, only bigger.

Alibaba infographicFor media watchers, however, the more interesting issue behind Alibaba’s filing will be what it means for Yahoo. Despite all of Yahoo CEO Marissa Mayer’s efforts to revive and reshape her lumbering U.S. online giant, it has been the company’s Alibaba stake that has buoyed Yahoo’s shares in recent months to reasonable levels. The IPO itself will likely far exceed the placeholder $1 billion amount in Alibaba’s paperwork, and is widely expected to come in at a level that would exceed the year’s biggest stock offering so far, of $15 billion. But speculators have invested in Yahoo as basically a tracking stock in the Chinese company ahead of the IPO. Now that the IPO is more than just a rumor, that value will be fully realized, and Mayer will have to find other ways to make Yahoo fly again. Perhaps Katie Couric’s new show will fit the bill.