“It’s a great day for humility,” Grant, the founder and editor of Grant’s Interest Rate Observer, told CNBC’s “Squawk Box.”

Financial markets across the globe tumbled after the U.K. voted in favor of leaving the EU, a decision markets were not expecting. Ahead of the vote, several polls and bookmakers showed support leaning toward the remain camp.

Jim Grant: Markets Just Got A Hard Lesson In Humility

Jim Grant