This paper studies the relation between the signs of recent returns (an up-down pattern) and the net trading of individual investors. For our comprehensive dataset from the Taiwan Stock Exchange, we find that following positive days, individual investors sell more stocks than they buy – a negative buy-sell imbalance – while following negative days, their imbalance is positive. More recent signs have stronger impacts on imbalance. The subsequent performance of this trading behavior is poor, indicating individual investors in Taiwan make suboptimal decisions, and their trade is unlikely to be information-based. Thus, the liquidity provision explanation in the literature is not applicable to our sample, and our results suggest behavioral reasons. We illustrate with a simple theoretical model that overconfidence can offer a potential explanation.