In December 2025, the global financial market welcomed a historic turning point. The Federal Reserve not only cut interest rates by 0.25% as scheduled but also, right after finishing its balance sheet reduction in November, quickly reversed course and announced the purchase of $40 billion in bonds within 30 days. This move marks the official start of the Federal Reserve's **third large-scale balance sheet expansion** in its history, following the 2008 subprime mortgage crisis and the 2020 COVID-19 pandemic. This is not just a simple adjustment of monetary policy, but a clear signal: the U.S. economy has once again entered a 'crisis moment'. #美联储降息周期