Penny Wise, Dollar Foolish: Buy–Sell Imbalances On and Around Round Numbers
研究发现股票交易者以整数为认知参考点，在整数下方1美分处买方流动性需求者过度买入，在整数上方1美分处过度卖出，这种失衡每年造成近10亿美元损失。
This paper provides evidence that stock traders focus on round numbers as cognitive reference points for value. Using a random sample of more than 100 million stock transactions, we find excess buying (selling) by liquidity demanders at all price points one penny below (above) round numbers. Further, the size of the buy–sell imbalance is monotonic in the roundness of the adjacent round number (i.e., largest adjacent to integers, second-largest adjacent to half-dollars, etc.). Conditioning on the price path, we find much stronger excess buying (selling) by liquidity demanders when the ask falls (bid rises) to reach the integer than when it crosses the integer. We discuss and test three explanations for these results. Finally, 24-hour returns also vary by price point, and buy–sell imbalances are a major determinant of that variation across price points. Buying (selling) by liquidity demanders below (above) round numbers yield losses approaching $1 billion per year. This paper was accepted by Brad Barber, Teck Ho, and Terrance Odean, special issue editors.