They knew it was coming. Broker-dealer Interactive Brokers Group Inc. IBKR, -5.02% has been planning for the Brexit vote since February, but, until late Thursday afternoon, the firm thought, like almost everyone else, the U.K. would vote to remain in the European Union. Polls earlier in the week had showed support for the “stay” camp growing, even as Federal Reserve Chairwoman Janet Yellen had cautioned on Tuesday that the U.K. leaving the European Union posed a risk. Fortunately, for the sake of the firm and its customers, Interactive Brokers was also ready for the “unexpected scenario,” according to Steve Sanders, ... (full story)