Central bank policy in a more perfect financial system

Financial innovation increases markets' liquidity and provides economic agents with new instruments to better handle risks, but it reduces the efficacy of monetary policy while strengthening the logic and force of the "unholy trinity". Increased liquidity of financial markets and increased leverage of financial positions imply that speculators can attack unsustainable fixed exchange rates faster and more powerfully than ever. The rapid innovation of new financial instruments in these markets also implies the futility to "throw sand in the wheels" through regulation or the introduction of transaction taxes. The higher asset substitutability generated by the emergence of derivatives makes the definition of "money," particularly of broad monetary aggregates, increasingly difficult. In a more complete financial market system central banks find it harder to predict the effect of a given monetary impulse on real output and employment with any reasonable precision. Discretionary monetary policies aimed at output and employment become more uncertain. Consequently, central banks should focus on the long-run goal of price stability.