A mild tangent here. There's a school of thought that insider trading can be a good thing, because insiders with knowledge can profit by making large stock tra

A mild tangent here. There's a school of thought that insider trading can be a good thing, because insiders with knowledge can profit by making large stock trades to bring a company's stock price in line with reality, and revealing to the world that they (an informed insider) think that the stock is overpriced (or underpriced). Any prospective investors can then use this information to make informed decisions about the purchase or sale of the stock. So, as you reference altruism - altruism is nice, but - in the absence of fraud - profit is a really nice incentive. (The main economic reason insider trading is illegal is that, in reality, this creates some horrible conflict-of-interest breach-of-fiduciary-duty scenarios. The main reason people want it to be illegal seems to be a sense that the stock market is a game and that everyone should be playing by the same "rules" so that they can't make a profit unless someone else can use a profit. Not that this encourages efficient markets in and of itself...)