Intraday Proprietary Traders and Short-term Mispricing

Whose trading corrects temporary mispricing? We document that intraday proprietary traders play this crucial role. Using trader-level transaction data, we examine the activities of different types of traders around a media-driven, clean shock to retail trading. Intraday proprietary traders are contrarian and contribute to an immediate and sustained price correction. Their trades generate returns from informed trading rather than liquidity provision. Conversely, longer-term proprietary traders who engage in much less contrarian trading make small returns from liquidity provision, not informed trading. Thus, policies designed to curb short-termism must account for the contributions of different types of traders to price discovery.