This paper measures the effects on stock proces of corporate investments in 5% or more of another company's equity securities. Such investments initiate a process that may end with a takeover, targeted repurchase, takeover by a third party, or sale of the shares. The total valuation effect of the investment for acquiring and target firms includes returns at disclosure of the investment position, the outcome announcement, and related intervening events. For example, the positive return for target firms at initial disclosure of the investment more than offsets the negative return at a targeted repurchase.

We examine the utility of the statistical factor model of the process generating stock returns in the context of event studies. For a variety of estimation procedures and experimental designs we find limited value added relative to the use of a simple market model. We would attribute this finding to misspecification of the statistical factor analysis model, and suspect that there exist more robust procedures for estimating the factor structure of stock returns.

Miller and Scholes (1978) hypothesize that the marginal tax rate on dividend income may be less than the marginal rate of tax on capital gains. Their hypothesis is dependent upon individuals utilizing existing provisions of the Code which serve to reduce the taxation of dividends. In this study, estimates of the marginal and effective rates of tax on dividend income for the year 1979 are presented using the Statistics of Income sample of returns. The average marginal rate of tax on dividend income is estimated to be 40%, while the average effective rate of tax is estimated to be 30%.