I study whether the capital gains tax is an impediment to selling by some investors and if so, to what degree associated delayed selling affects stock prices. I find that selling decisions by institutions serving tax-sensitive clients are sensitive to cumulative capital gains, a pattern not observed for institutions with predominantly tax-exempt clients. Moreover, tax-related underselling impacts stock prices during large earnings surprises for stocks held primarily by tax-sensitive investors. The corresponding price reactions are less negative (more positive) with higher cumulative capital gains. This price pressure pattern is more severe when arbitrage is more costly.