The credit rating agency, Fitch, caused a stir yesterday when it downgraded the United States' credit rating from AAA to AA plus. This came less than a week since Federal Reserve staff stopped forecasting a recession on the horizon. So what gives? Today, we talk to an economist to break down the reasons why Fitch no longer views the US as among the safest of bets. *For sponsor-free episodes of The Indicator from Planet Money, subscribe to Planet Money+ via Apple Podcasts or at *plus.npr.org.)**Learn more about sponsor message choices: podcastchoices.com/adchoices)NPR Privacy Policy)