Alicia H Munnell & Steven A Sass 
Social Security and the Stock Market [PDF ebook] 

Munnell and Sass explore whether equities could help solve the woes facing the U.S. retirement income system in general, and the Social Security shortfall in particular. They examine the experiences of three nations that added equities to the investment mix of their retirement systems-the U.K., Australia, and Canada. As these experiences show, while equities promise higher returns than government bonds, how they are implemented-as add-ons, carve-outs, or as trust fund supplements-matters greatly.