It’s pretty efficient at assimilating obvious revelations. You have to be quick to trade on the news, and you’re not going to find many arbitrage opportunities. There’s no reason why it would be particularly efficient at pricing long term outcomes. It reflects some sort of consensus or balance of opinions, but those things could simply be wrong. That said, even if you’re right about something, there’s so many factors to account for, it’s not going to be easy to profit. Personally I have most of my savings in retirement tracker funds (global equities), but I’m also building a portfolio of handpicked stocks/bets, aiming for 20, each with the same starting investment. Maybe it won’t be successful but at least it will be fun and minimise the regret of not acting on my insights/convictions. The diversification should stop it from being a disaster.