The Federal Reserve and other central banks manipulate interest rates every day, James Grant of Grantâs Interest Rate Observer told CNBCâs âClosing Bellâ on Thursday. âThe Fed is in the business of trying to manipulate markets, the macro economy, interest rates, unemployment and inflation through various monetary means, including the twisting around of yield curves and interest rates,â Grant said. Grant added, âThe Federal Reserve fixes rates on principle. They have âoperation twistâ that manipulates the credit markets. They have quantitative easing that manipulates bond yields.â