1. They may allow for some amount of short selling "against the box" or may restrict short selling completely. We provide both examples. From AIM Aggressive Growth: Aggressive Growth may not make short sales of securities (unless at all times when a short position is open it either owns an amount of such securities or owns securities which, without payment of any further consideration, are convertible into or exchangeable for securities of the same issue as, and equal in amount to, the securities sold short, and unless not more than 10 percent of the Fund's total assets (taken at current value) is held for such sales at any one time);From AIM Charter: Charter may not sell short
2. The impact of new issues of derivative securities and the underlying blue chip securities