The U.S. Treasury raised the size of its planned buyback operation for Treasurys maturing in 10 to 20 years to $6 billion, triple the typical amount.

The Treasury Department announced last month that it would at least double buybacks of longer-term bonds to $4 billion.

The U.S. 10-year Treasury yield rose after the announcement to 4.84% from 4.81%, its highest intraday level since November 2023. The 30-year yield rose to 5.29% from 5.26%. The two-year yield edged up to 4.42% from 4.41%.

Treasury Secretary Scott Bessent said he doesn't believe Treasury yields reflect the underlying fundamentals following the announcement to increase buybacks in longer-end bonds. Separately, he said he does not believe he could change the equilibrium price of Treasurys.

Instead, Bessent said his job is to "speed things down" and make sure market participants know that things may not be on "a one-way trip."

Long-dated bond yields have risen globally amid concerns of mounting government debt, broader economic uncertainty and inflation from higher oil prices tied to the conflict in Iran. Brent oil crossed above $100-a-barrel for the first time since July on Wednesday after the latest round of strikes in the Middle East.

"The size of the intervention is rather small ... and not likely to sway the inclination of investors to charge a higher risk premium and push yields higher as inflation continues to rise and concerns about the sustainability of the U.S. fiscal path mount," said Joe Brusuelas, chief economist at RSM.

In addition, Treasury straying away from its "regular and predictable" mantra could increase term premium in the long run, says Molly Brooks, research strategist at TD Securities.

"We would not be surprised if we are not given much notice for long-end auction size decreases, which could be sooner than we initially anticipated before the buyback interventions were announced," Brooks wrote.

The buyback operation is scheduled for Thursday.