While many countries are following the lead of the United States in making insider trading illegal, its moral status is still controversial. I summarise the scholarly debate over the fairness of insider trading and lay bare the assumptions about fairness implicit in that debate. I focus on the question whether those assumptions can be defended independently of a more comprehensive theory of social justice. Current analyses presuppose that we can intelligently discuss what the social rules regarding insider trading should be (...) while ignoring questions about the broader principles of justice that should be adopted and the extent to which existing institutions realise those principles. I argue that such questions must be addressed. I then employ an egalitarian conception of social justice to analyse insider trading. I thereby illustrate how a more systematic approach, grounded in a comprehensive theory of justice, transforms the debate about the fairness of insider trading. (shrink)