When a central bank sells government bonds in an open market operation, it is likely to lead to an increase in the money supply and a decrease in interest rates in the short run.

When a central bank sells government bonds, it means they are taking money out of the economy. Investors buy these bonds, which reduces the amount of money available for spending or lending. As a result, people have less money to use, which can lead to lower interest rates in the short run because banks may have more bonds and fewer deposits to lend. For example, if a central bank sells bonds worth $1 million, banks may have less cash available to lend, causing them to lower interest rates to encourage borrowing. This process is part of how central banks manage the economy and control inflation.