Yahoo owns 22.4% of the Chinese e-commerce company so it, and its shareholders, have a lot at stake in Alibaba’s disclosure today that it expects to price its shares between $60 to $66 apiece on September 18, the day before they begin trading on the New York Stock Exchange. The announcement, in an SEC filing, means that Alibaba could raise $21.1B — the most ever for a U.S. IPO. At the midrange of the stock prices, it would value the company at about $156B — almost as much as Amazon, and ahead of the two most valuable traditional media companies: Disney and Comcast. Alibaba execs plan to spend next week traveling around the globe to make their sales pitch to money managers before they set the final price for the shares. Yahoo is obligated to sell some of its stock to lower its stake to 16.3%. Shares will trade under the symbol “BABA.”

Alibaba says that it had 279M active buyers in June, up nearly 51% from the month in 2013. It generated $3.77B in net income in the year ending in March on revenues of $8.46B.