Among the investors attending the event was Mario Gabelli, CEO of Gabelli Asset Management. Alibaba is seeking to raise more than $21 billion in an initial public offering that will value the company at up to $163 billion and rank as the largest-ever technology debut in the United States. Alibaba expects to price the IPO at $60 to $66 per American Depository Share. It will list shares on the New York Stock Exchange and start trading later this month.