1. Today, the impact of the "up-tick" rules has been weakened by the advent of decimalization of securities prices. Still, recent commentators have argued that the primary constraints on short selling are imposed by the tax laws. See Michael Powers, David Schizer and Martin Shubik, Market Bubbles, Wasteful Avoidance, and Tax and Regulatory Constraints on Short Sales (Working Paper 2003) (detailing both tax and regulatory constraints). In recommending some relaxation of these constraints;Owen A Jones;J. Fin. Econ,1976