Although the effects of pure diversification and synergistic mergers on market valuation have been widely discussed and there have been a number of studies estimating. merger performance using the two-parameter model of Sharpe-Lintner, the investigation of the corporate determinants of beta is of recent vintage. A variation on this theme, namely whether merger activity is impounded into beta and its speed of being impounded, is the focus of the Joehnk-Nielsen (J-N) study.