Alibaba will not be listing in the U.S. any time soon, but your Broker can help you buy shares:
SUNDAY Dec. 16 is when the action starts for US investors trading into the Hong Kong market for Alibaba stock [ Symbol: 1688.HK ]. That's when the SEC's 40-day trading ban on a foreign-issued IPO ends.
Hong Kong is a day ahead of the Pacific International Date Line, so its really Monday the l7th there at the same time.
Your Broker or your Bank's International Services Trading Rep can place the trade for you 24/7 on the Hong Kong Exchange.
The thing to do ahead of time is phone up and find out the fees and rules and restrictions, e.g. small additional fees apply, must be same-day trades, no limit orders allowed unless within Hong Kong $1 etc.
Just look at a '3 month' view of Alibaba [ 1688.HK ] [even if it has not been that long since the Nov. 6 IPO on the Hong Kong exchange] for a pretty picture of a nice uptick. Initial profit-taking has occurred and it has rebounded nicely.
As for 'What's up" with Yahoo stock not hitting expected highs by now, read other posts on this board about institutional positioning and consolidation.
Both Alibaba and Yahoo will be running up shortly. Be patient. Buy both!