Stock market reactions to changes in the FTSE SmallCap and S&P/TSX SmallCap indices

Stocks added to (deleted from) the Russell 2000 and the S&P 600 indexes experience positive (negative) abnormal returns following the announcement. However, researchers disagree on whether these abnormal returns are permanent or temporary and offer competing explanations. I address this controversy by examining market reactions for firms that are added to or deleted from the FTSE Small Cap index (the main testing sample) and the S&P/TSX SmallCap index (the comparison sample). For the main testing sample, all stocks except pure additions, experience a permanent price change that is accompanied by a permanent change in liquidity. However, for the comparison sample, abnormal returns over the announcement period fully reverted within 30 days. In further examination of stock liquidity for the main testing sample, sample stocks experience permanent change in liquidity. Taken together, the observed results support the price pressure and liquidity hypotheses.