If the Fed loses its independence then U.S. bond investors should don protective helmets. Photo by Chip Somodevilla/Getty Images) S&P Global reaffirmed its AA+ sovereign credit rating for the U.S. in a new report late Monday but it made one thing clear: the independence of the Federal Reserve is of paramount importance if that rating is to be maintained. That's because when analyst Jeff Sexton assessed the dynamics of U.S. debt, many of the metrics plugged into his model were problematic. Implicit within his commentary was a warning that without the credibility, flexibility and stability the Fed provides, and its ... (full story)