Welcome to Market Catalyst. I'm Julie Hyman. We are 30 minutes into the US trading day.Let's get to the three market catalysts we're watching this hour. First up, are AI stocks overvalued. It's the question investors have been asking and we'll dig in for today's investor playbook.Plus, Warner Brothers Discovery missing earnings estimates as the company plans for a split. Full coverage on the entertainment industry ahead. And the Supreme Court hears arguments on President Trump's sweeping global tariffs.We'l ...