Yahoo (NASDAQ:YHOO) has been riding the Alibaba wave, with its stock gaining in the last month due to its giant share of the Chinese e-commerce giant, whose much-anticipated initial public offering on Sept. 19 could be the biggest tech IPO of all time. But don't expect that surge to last, say analysts.

The Internet giant is one of just two publicly traded companies with a stake in Alibaba and its 22.4 percent share could be worth at least $36 billion at Alibaba's IPO price range of $60 to $66. That giant amount -- plus cash on hand of $1-2 billion, only $1 billion in debt and a nice stake in Yahoo Japan -- adds up to a value of about $42 billion, notes Marketwatch. And its business is pretty stable, earning $1.2 billion in profit last year. 

Yet its market valuation -- the stock price was at $42.55 per share on Monday, twice its price a year and a half ago -- still lags behind at $41 billion. It's the reverse scenario of many high-flying tech stocks, in which market value seems otherworldly compared to its core assets. What's going on?

There are several reasons for the apparent disconnect, say analysts. One problem is that Alibaba stock might be considered one of Yahoo's few remaining assets, says Webush Securities analyst Gil Luria. Under Marissa Meyer, its seventh CEO since 2001, Yahoo has made plenty of high-profile acquisitions, including Tumblr, but the consensus is still out on whether her turnaround plan will bear fruit since none of these changes have "led to significant growth in revenue and profits for the purple portal," reports CNNMoney. “There’s a consensus in the market that core Yahoo business isn’t valued very highly.” 

Secondly, the value of the stake in Alibaba will likely end up much lower after taxes -- at 35 percent tax rate, Yahoo's $36 billion is worth only $23 billion. It has committed to sell 140 million shares, which should net about $8 billion (or $5 billion after taxes). Yahoo does hold a portion of its Alibaba stock in Hong Kong, where share sales are exempt from capital gains taxes, according to a July 9 Cantor Fitzgerald note. But in this case, the cash would have to remain overseas, as reported by the Wall Street Journal.

Third, not many investors have confidence that Yahoo will know how to use its new billions. The company is returning only half of its initial IPO sale to shareholders through special dividends and stock buybacks, not specifying how the rest would be spentaccording to Bloomberg.

Lastly, investors may just want to bypass Yahoo for now and wait to go right after its most valuable asset by buying stock in Alibaba.

“There’s a consensus in the market that core Yahoo business isn’t valued very highly,” Wedbush Securities analyst Gil Luria told International Business Times.

“Once investors can buy Alibaba directly, and assuming there won’t be any arbitrage, that could limit demand for Yahoo,” Luria said. “People who want to buy Alibaba will just buy Alibaba.”

Yahoo stock is still up 8.3 percent year-to-date, and spiked 29 percent since July to hit a high of $42.8 on Monday. The only other public holding company of Alibaba is Japanese telecommunications firm Softbank (TYO:9984,) which has an even larger piece at 32 percent, but also has other valuable assets that should keep shareholders interested.  

Alibaba is expected to make its debut on Sept. 19 with ticker symbol BABA. 

“Alibaba is the only good decision Yahoo has made in the past several years, everything else has gone south for them,” Kinshuk Jerath, professor at Columbia Business School, said to IBTimes. 

“If you take out that chunk, not much is left,” Jerath said.  “People have really lost faith in the company.”