•We study the joint effects of regulations forbidding informed trading and shorting of assets and cash.•Allowing short positions and allowing informed trading leads to less mispricing and smaller spreads.•Despite evidence in the literature, we find no strong interaction effects between the regulations we study. Modern capital markets are subject to many interventions and regulations, some of which curtail the implementation of specific trading strategies in a market. While we understand much of these regulations’ individual effects, the picture is less clear about their joint effects. This paper considers the interaction of two regulations, namely rules limiting shorting of assets and cash, and rules limiting insider trading. For these regulations, prior research shows spikes in short-selling activity around the revelation of insider information, which different studies trace to different causes. Among other results, we find that both allowing short positions and allowing informed trading causes informed traders to increase their market activity and causes mispricing and spreads to diminish. Nevertheless, we find no evidence for significant interaction effects between the two regulations.