It's not news that major changes in a company's course – such as acquisitions – cause variation in the share prices of the companies involved. But does minority shareholder activism produce sufficient impact to change share prices? The study Shareholder Activism through the Proxy Process, by Luc Renneboog (Tilburg University) and Peter Szilagyi (Cambridge University), says yes.

Analyzing 2.8 thousand proposals submitted between 1996 and 2005 at 2 thousand American companies, the authors found abnormal share return patterns starting on the dates when proposals made by activist shareholders became known to the public. On average, the companies' shares went up 0.25% over the analyzed period. This shows that changes recommended by investors are interpreted by the market as relevant to the company, according to the study.

Depending on the proponent, the variation becomes even more positive. Proposals submitted by powerful American pension funds stimulated an average share appreciation of 1.08%. Requests from investment funds and investor groups pulled the quotations up by 0.53% and 0.34%, respectively. The intensity of variation also changed according to the subject matter. Proposals concerning the company's acquisition or its board caused more intense variation (0.59% and 0.3%, respectively) than did routine matters (0.16%).