@techreport{NBERw10218, title = "Aggregate Short Interest and Market Valuations", author = "Owen A. Lamont and Jeremy C. Stein", institution = "National Bureau of Economic Research", type = "Working Paper", series = "Working Paper Series", number = "10218", year = "2004", month = "January", URL = "http://www.nber.org/papers/w10218", abstract = {We examine some basic data on the evolution of aggregate short interest, both during the dot-com era, and at other times in history. Total short interest moves in a countercyclical fashion. For example, short interest in NASDAQ stocks actually declines as the NASDAQ index approaches its peak. Moreover, this decline does not seem to reflect a substitution away from outright short-selling and towards put options, as the ratio of put-to-call volume displays the same countercyclical tendency. The evidence suggests that: i) arbitrageurs are reluctant to bet against aggregate mispricings; and ii) short-selling does not play a particularly helpful role in stabilizing the overall stock market.}, }