The Regulation of Outsider Trading in EU and the US

This paper examines the regulation of outsider trading in EU and the US, highlighting the differences between the two legal systems and investigating the main implications of the different regulatory choices made in the two jurisdictions. Outsider trading can be defined as the sale or purchase of listed securities on the basis of material nonpublic information by individuals who do not qualify as “insiders”. While US law leaves considerable room to outsider trading, EU law unconditionally prohibits it. Constraining outsiders’ exploitation of material nonpublic information has a sound efficiency-grounded justification, but an unconditional ban on all informed trading by outsiders appears harmful: it hinders investors’ incentives in ferreting out new information, decreasing market efficiency and increasing agency costs of publicly traded firms. US law, with its selective limitation of outsider trading, appears largely immune from these consequences. EU law, to the contrary, has the potential to carry on such drawbacks.