President Trump took a swipe at credit card issuers this week, vowing his administration wouldn’t let consumers be “ripped off” by high interest rates and sending bank stocks and financial-sector ETFs skidding downward. Like many things in the Trump era, it’s hard to tell what is noise and what is an actual threat to businesses. In this case, the president told credit card issuers to cap interest rates at 10% (about half the current average across the industry) or risk running afoul of the law. But it doe ...