If the IPO values the company at $200 billion, Alibaba would have been about 3.3 percent of the index. There are more than $54 billion in ETF assets alone linked to the index, which means at least $1.7 billion would have flown into Alibaba shares.
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The chance to get on Nasdaq 100 was a selling point for Facebook itself. In the lead-up to the Facebook IPO, Nasdaq reduced the amount of time a qualifying firm needs to be listed on Nasdaq in order to be added in the index to three months from a year.
Alibaba doesn't qualify to be on many of the world's major indices, since it is registered in the Cayman Islands. The behemoth S&P 500 Index, which has a market capitalization of $18.6 trillion, only lists U.S. companies.
The Chinese firm is not eligible to be part of the biggest MSCI or FTSE indices for other reasons, although MSCI is looking at changing its index rules in a way that could put Alibaba on a major index.
And finally, Alibaba gave up a chance for mainland Chinese to invest, since China-based money manager Guotai Asset Management's Guotai Nasdaq 100 Index trades on the Shanghai Stock Exchange.
"It falls into this no man's land of indexing," said Dennis Hudachek, a senior ETF specialist with ETF.com, an expert on exchange-traded funds.