Jurrien Timmer, global macro director at Fidelity Investments, warns that the US dollar's global dominance could be at risk if the Federal Reserve intervenes in the bond market. Timmer suggests that if the Fed purchases debt securities to control interest rates, the US dollar index (DXY), currently at 98, could decline further. This year, the DXY has already dropped over 9%. Timmer highlights the potential need for Fed intervention if GDP growth does not exceed interest rates on government debt. He points to the growing gap between Treasury sales and Fed purchases, which could lead to an unsustainable debt spiral if the term premium continues to rise, potentially forcing the Fed to re-enter the bond market.