On November 17, 1988, the board of directors of Nestlé AG decided to allow foreign investors to hold Nestlé registered stock, reversing a longstanding practice. This decision had a tremendous impact on the prices of the firm's three classes of common stock, as well as on the prices of several other corporations traded on the Zürich stock exchange. These price changes can be explained by the hypothesis that demand curves slope down.

We examine whether sample selection bias explains the difference in returns between ‘value’ stocks (high book-to-market ratios) and ‘glamour’ stocks (low book-to-market ratios). Selection bias on Compustat is not a severe problem: for CRSP primary domestic firms, the proportion missing from Compustat is not large and the average return is not very different from the Compustat sample. Mechanical problems with matching Cusip identifiers account for much of the discrepancy between CRSP and Compustat. The superior performance of value stocks is confirmed for the top quintile of NYSE-Amex stocks, using a sample free from selection bias.