Jerome "Jay" Powell was sworn in as Chair of the Federal Reserve amidst wild fluctuations in U.S. stock markets. Analysts attributed sliding stock prices to fears over inflation. Mr. Powell, who follows former Fed Chair Janet Yellen, introduced himself via a video clip on the Fed's website. Weekly readings on mortgage rates and new jobless claims were also released. New Fed Chair Promises "Transparency" in Video Introduction In a video introduction posted on the Fed's website, new Fed Chair Jay Powell promised that the Fed would explain "what we are doing and why we are doing it." Mr. Powell did not address…