If you’ve watched any professional sports this year, chances are you’ve seen ad after ad pushing parlay bets. WSJ’s Katherine Sayre explains how parlays became big business for sports betting companies. Further Listening: - How a Psychiatrist Lost $400,000 on Gambling Apps - Disney Gets Into Gambling Further Reading: - America Has Fallen in Love With Long-Shot Sports Bets - This Year’s Big NFL Winners: Fans, Not Sportsbooks Learn more about your ad choices. Visit megaphone.fm/adchoices