Companies with total return to shareholders ranking in the top quartile give their high-performing employees a disproportionately large share of the merit budget and use performance ratings to determine stock-option participation. The just-issued study by New York-based Towers Perrin said that stock options and grants are the top reason employees stay at high-performance companies. The other reasons in the top five: challenging work and promotion opportunities, the quality of top leadership, the work climate, and variable pay.