Kevin Warsh, chairman of the US Federal Reserve nominee for US President Donald Trump, during a Senate Banking, Housing, and Urban Affairs Committee confirmation hearing in Washington, DC, US, on Tuesday, April 21, 2026. Graeme Sloan | Bloomberg | Getty Images Most people don't know and don't have much reason to care what a currency swap line is, except that the financial instrument could soon help markets understand what Federal Reserve Chair nominee Kevin Warsh 's unique ideas about Fed independence really mean. Warsh has said categorically the Fed should be "strictly independent" in the making of monetary policy.…