Jeffrey Ma was a member of the MIT blackjack team, which utilized sophisticated card-counting strategies to beat casinos at blackjack worldwide in the mid-1990s, and was the basis for the main character of the book Bringing Down the House and the film 21. He is the author of The House Advantage. He has been the technology lead for two internet startups and was an options trader on the Chicago Board of Options Exchange. He co-founded PROTRADE, a sports stock market website, and consults for professional sports teams including the Portland Trail Blazers and the San Francisco 49ers. He lives in San Francisco, CA.