I disagree with ProPublica's take. If it was as simple as "pay just fractions of a penny per share... watch as all the gains..." then we would all do it. Not just with Roth IRAs, but with our entire portfolios. The reason we don't all do this is because startups are very very risky. Some people will succeed and walk away with windfalls. Other people will lose their shirts. If there was arbitrage, there would be a an "app for that" and there would be more billionaires walking around.