"The current maximum volume of two billion dollars per operation will be at least four billion dollars per operation," the department writes in a press release.
The yield on the US 30-year Treasury bond is falling to 5.19 percent, which can be compared with a peak above 5.30 percent as recently as Tuesday - the highest interest rate level since 2007.
According to the Ministry of Finance, the increased buybacks, which are to begin on September 9, are a way to boost liquidity in the market.
The futures market is pointing up ahead of Wednesday's stock market trading on Wall Street after the announcement.
