Why can't a woman bid more like a man?

In this study, we investigate gender differences and menstrual cycle effects in first-price and second-price sealed-bid auctions with independent private values in a laboratory setting. We find that women bid significantly higher and earn significantly less than men do in the first-price auction, while we find no evidence of a gender difference in bidding in the second-price auction. At a biological level, we find a sine-like pattern of bidding in the first-price auction throughout the menstrual cycle, with higher bidding in the follicular phase and lower bidding in the luteal phase. Further analysis shows almost all of the variation is driven by contraceptive pill users.