[baddox]

I think the main trouble I'm having with your argument is the idea of it "harming" someone. While that seems to perhaps be true in the most technical sense, I'm not sure it's a sufficient argument for banning insider trading. After all, many things which harm people are not generally considered to be bad. For instance, if someone opens a restaurant Ina town, and runs the restaurant very efficient while offering a high quality product, that could absolutely harm other competing restaurant owners. And yet most people do not condemn the practice of opening a restaurant and operating it well.

[lambdapie]

You are right that "harming" someone is not a sufficient reason to ban an action. And as others have pointed out, researching a company carefully causes the same kind of "harm", and certainly shouldn't be banned. My intention was to refute people (like in the article I linked) who argue that all market participants benefit from and insider trader's transaction.

Once we see that this isn't the case, it becomes necessary to do a cost benefit analysis to determine the true effect of allowing insider trading. But as you say, this should be done on a utilitarian basis, not on some imagined "rights" of the counterparty to insider trading. (EDIT: I don't mean to imply that economic analysis from a utilitarian POV can't clarify what we should think of as people's rights, but rather that as you said, causing someone else to have a negative outcome does not prove that someone's rights are being violated)

[Natanael_L]

Should judges be able to trade on the information about companies be is about to deliver judgements for? Should city planners be allowed to trade on the information on approvals / denials before they're announced?

[baddox]

I would hope that both of those examples would be prohibited by the terms of their employment.