This paper studies the implications of banking competition for capital markets and monetary policy. In particular, I develop a two-sector monetary growth model in which a group of agents is exposed to liquidity shocks and money is essential. Banks insure depositors against such risk and invest in the economy's assets. In this setting, I compare an economy with a perfectly competitive banking sector to an economy with a fully concentrated financial sector. Unlike previous work, banks can have market power in both deposits and capital markets. Compared to a perfectly competitive financial sector, I demonstrate that a monopolistic banking system can have substantial adverse consequences on capital formation, assets prices, and the degree of risk sharing. Furthermore, multiple steady-states can emerge and the economy becomes subject to poverty traps. More importantly, market power in financial markets may overturn the Tobin effect present under a perfectly competitive financial sector. This necessarily happens in economies with high degrees of liquidity risk and low levels of capital formation. (C) 2011 Elsevier B.V. All rights reserved.