United States - 6-Month Treasury Bill Secondary Market Rate was 3.86% in September of 2025, according to the United States Federal Reserve. Historically, United States - 6-Month Treasury Bill Secondary Market Rate reached a record high of 15.93 in May of 1981 and a record low of 0.02 in August of 2011. Trading Economics provides the current actual value, an historical data chart and related indicators for United States - 6-Month Treasury Bill Secondary Market Rate - last updated from the United States Federal Reserve on September of 2025.