2. Concurrently with the foregoing, and as provided in the Treaties and in accordance with the procedures set out therein, these activities shall include a single currency, the euro, and the definition and conduct of a single monetary policy and exchange-rate policy the primary objective of both of which shall be to maintain price stability and, without prejudice to this objective, to support the general economic policies in the Union, in accordance with the principle of an open market economy with free competition.

3. These activities of the Member States and the Union shall entail compliance with the following guiding principles: 

    stable prices, 

    sound public finances and monetary conditions and 

    a sustainable balance of payments.