Credit expansion in the US can either be a good sign of financial growth or a warning of a future economic downturn. By analyzing monthly data, researchers found that while credit growth can lead to higher output, it can also trigger negative responses from monetary policies. Financial stress, like credit spread shocks, can cause output and credit levels to drop. Surprisingly, neither credit growth nor spreads predicted the 2008-2009 crisis well, but spreads did help forecast during the crisis.