This study investigates the effect of differential capital gains tax rates on investor trading and share prices in a unique market setting that facilitates the resolution of conflicting prior evidence of holding period tax incentives. In particular, we examine whether the concessionary tax treatment of long-term capital gains increases the supply of shares that qualify for long-term status, thereby causing downward price pressure. We find evidence of abnormal seller-initiated trading following the 12-month anniversary of listing for IPO firms that appreciate in price (‘winners’) and report no such evidence for firms that decline in price (‘losers’). Consistent with the tax concessions being greater for individual than institutional investors, we report that abnormal seller-initiated trading is mitigated by higher levels of ownership by institutional investors. We also report limited evidence, for winners, of declining share prices upon qualifying for long-term tax status.