Jim Chanos, founder of Kynikos Associates. Business Insider The special-acquisition company frenzy is being driven by unrestrained speculation and may not yield expected returns, Bloomberg reported legendary short-seller Jim Chanos as saying.History shows so-called "blank-check" companies do not perform well, but a burst of speculation has brought them back into focus, Chanos said at a conference on Tuesday.Chanos criticized companies for putting aside metrics such as revenue and earnings, and focusing instead on the total market size they can win.He said the idea is "how big is what you're chasing, forgetting for a second that everybody else is chasing those same markets."Visit Business Insider's homepage for more stories.The boom in SPACs is driven by heavy speculation and may not produce expected returns, as these investment vehicles don't perform well historically, Bloomberg reported short-seller Jim Chanos as saying."We are going to blow through the records of 1999 and 2000 in terms of new issuance," Chanos said at a conference in New York on Tuesday.