Despite relatively high short-term borrowing costs, the possibility remains that the Fed's target for short-term interest rates will return to zero over the next few years, according to new research by the Federal Reserve Bank of New York and the Federal Reserve Bank of San Francisco. The report, co-authored by New York Fed President William Williams, shows that the medium- and long-term risk of a return to ultra-low Fed interest rate targets "is currently at the low end of the observation range of the past 15 years". But the possibility of a return to near-zero rates in the medium to long term "remains significant", the researchers added, given the recent rise in uncertainty.