Menstrual cycle and competitive bidding

► We correlate bidding and profits in symmetric independent private value second-price auctions with menstrual cycle information in over 400 participants. ► Naturally cycling women bid significantly higher than men and earn significantly lower profits than men except during the midcycle when fecundity is highest. ► Women on hormonal contraceptives bid significantly higher and earn substantially lower profits than men. ► We discuss differences to Chen et al. (2013).