Here's a valuation conundrum for you: Web search company Yahoo has a market capitalization of about $41 billion. Its 16 percent ownership stake in the Chinese e-commerce giant, Alibaba, is worth approximately $37 billion.

Without Alibaba, it seems, Yahoo's core value would only be about $4 billion. That would put Yahoo's main business in a league with AOL, whose market cap is $3.5 billion, and online daily deals retailer Zulily, whose market cap is currently about $4.5 billion.

It's a good lesson for any small business that partners with others or invests in an--at the time--smaller company. That company could grow and outpace you.

Such strange inversions aren't entirely unheard of--the ill-fated AOL and Time Warner merger in 2000 comes to mind--but the valuation puts Yahoo in a dicey spot. Investors clearly see Yahoo's value is all about Alibaba now. For proof of that, look no further than what happened to Yahoo's share price when it sold off part of its Alibaba stake Friday, netting about $9 billion in the process. Yahoo's stock price has fallen by more than 8 percent since then.

But Yahoo's valuation being caught up with Albaba's isn't necessarily a bad thing, says Kinshuk Jerath, an assoicate professor at Columbia Business School in New York City. Yahoo has been struggling to reinvent itself and maintain relevancy for years. Now's its chance. 

"Yahoo has good traffic in the U.S., and a good brand, and Alibaba could partner with it to enter the U.S. retail market," Jerath says.

Jerath's not suggesting that Yahoo, which ranks third in the U.S. for total Internet traffic, will become an Amazon, where it owns merchandise which it sells online from vast warehouses to consumers. Rather, Jerath means that Yahoo could have a hand in building an online marketplace, like the one Alibaba already operates in China. That platform connects buyers and sellers, without Alibaba owning any of the product.

Some of Alibaba's recent activity, such as the launch this summer of Esty-like retailer 11 Main and its $200 million venture investments in both the daily deals site Shoprunner.com and messaging app company Tango seem to suggest it's putting the pieces of a marketplace together. And Yahoo may now be part of Alibaba's larger plan to drive traffic to its blossoming U.S. enterprise.