I don’t pay too much attention to stock market commentary, but another warning light on the economic dash might be that margin calls appear to have spiked. You ignore most of those warning lights most of the time, but sometimes they mean something, and if there are more of them over time and they are all flashing at once you might want to do something about it. Margin calls mean investors who have borrowed money from their brokers to buy stocks are being told by the brokers they have to pay the loans back, which forces them to sell some of what they have. It suggests the brokers are nervous the market might fall. If it actually starts to fall, this can accelerate the fall because people are then forced to sell when they don’t want to and everybody else is selling. And margin calls are just the visible tip of a debt iceberg, most of which lies unseen beneath the surface. This blog is called Wolf Street.