Open market operations are a group of indirect market based monetary instruments through which the National Bank sells and purchases securities. These instruments are used for influencing the level of the short-term interest rates, i.e. the level of banks' liquidity. The increase in the interest rate with these operations indicates more restrictive monetary policy and vice versa, the reduction of the interest rate acts towards relaxation of the monetary policy. 

The structural position of the banking system relative to the central bank led to a long-term dominance of the operations for withdrawal of liquid assets from the banking system through issuing securities (Central Bank bills) by the National Bank. On the other hand, in order to satisfy short-term liquidity shortage in the banking system, the National Bank conducts repo operations to provide liquidity. Outright purchase and sale of securities on the secondary market are less present.

In conditions of more significant deviations in the liquidity projections which lead to unplanned excess or lack of liquidity in the overall banking system, National Bank may apply (extraordinary) fine tuning operations in order to avoid significant fluctuations in the level of liquidity of the banking system and the interest rates on the money markets.

Open market operations consist of: