The bid in U.S. government bonds faded on Wednesday, with rising oil prices adding upward pressure on yields across the curve. The 30-year Treasury yield climbed back above 5.2%, erasing the relief from the previous session's 9-basis-point drop that followed the Treasury Department's expanded buyback proposal.

British gilts also came under pressure, while European fixed-income markets showed a mixed picture, with German Bunds edging slightly stronger. The U.S. yield curve steepened modestly, with the 2s/10s and 2s30s spreads widening by less than 1 basis point compared with Tuesday's close.

The 10-year Treasury yield was hovering around 4.6755%, up 3 basis points on the day. German Bunds outperformed their U.S. counterparts by roughly 4 basis points, while the 10-year gilt yield added 1 basis point.

The Treasury's auction calendar for the day included a $8 billion reopening of the 30-year Treasury Inflation-Protected Securities (TIPS).