Warsh could guide to a smaller role in day-to-day markets, while also setting clearer rules for how and when it should intervene.

Never before has a chair of the US Federal Reserve been so controversial. Who is Kevin Warsh? Can he preserve the Fed's independence, or will he become Donald Trump's puppet?

Never before has a chair of the US Federal Reserve been so controversial. Who is Kevin Warsh? Can he preserve the Fed's independence, or will he become Donald Trump's puppet?