Recently, there has been an attention-grabbing data change in the US financial markets: the yields of 3-year, 5-year, and 7-year treasury bonds have successively fallen below 4%. This phenomenon reflects adjustments in market expectations for economic prospects and may also signal potential shifts in monetary policy. With increased uncertainty in global economic growth, investors' demand for safe assets has risen, driving the downward trend in US Treasury yields. Specific data shows that the yields of these short-term and medium-to-long-term bonds have dropped to 3.98%, 3.96%, and 3.94%, respectively, setting recent lows. This change not only has significant implications for the domestic US economy but also has ripple effects on the global financial markets and is worth close monitoring.