The flight to safety sent the yield on the 10-year Treasury note — used as a benchmark for mortgage rates and auto loans — falling to a low of 1.595%, the lowest since autumn 2016. The yield on the 30-year Treasury bond bottomed around 2.12%, near its all-time low reached in 2016. Yields pared some of their declines later in the session, but held steady near multiyear lows.

The 10-year Treasury rate is about 40 basis points below its level one month ago, down more than 35 basis points in August alone and representing a sizable move for the relative stable U.S. bond market. The yield ended July above 2%.

Bond yields move inversely to their prices; yields fall when investors demand Treasurys.

The head-turning moves in the bond market weren't isolated to the United States, however, as rates in Germany and the United Kingdom clinched all-time lows across the board on Wednesday.