The billionaire founder of Interactive Brokers warns that stocks have another 20% downside as investors underestimate the impact a stagnant economy will have on earnings

Thomas Peterffy, the billionaire founder of Interactive Brokers, doesn’t see the Federal Reserve succeeding in its goal to bring inflation back down to its long-term target of 2%. Instead, he sees the Consumer Price Index having difficulty falling below 4.5%. That doesn’t mean, however, that the Federal Reserve will remain committed to reining in inflation,…