We try to make Keynes' approach compatible with an endogenous theory of the money supply. For that purpose, the principle of liquidity preference is generalized within a competitive banking framework. Private banks can impose a monetary rationing independently of the central bank. Then, we analyse the consequences of a monetary policy shock on the financial behaviour of banks. We clarify the dynamic process between the monetary policy and net investment within a Minskyan approach. First, we build a Post-Keynesian stock-flow consistent model with a private-bank sector introducing more realistic features. Second, we perform some simulations.

This paper presents the 'KMGT' (Keynes-Metzler-Goodwin-Tobin) portfolio model and studies its stability properties. The approach to macrodynamic modelling taken here extends the KMG model of , focusing in particular on the incorporation of financial markets and policy issues. The original KMG model considered three asset markets (equities, bonds and money) but depicted them in a rudimentary way so that they had little influence on the real side of the model. The only financial market influencing the real side of the economy was the money market (via an LM curve theory of interest). Here Tobin's portfolio choice theory models the demand for each asset in such a way that the total amount of assets that households want to hold equals their net wealth, which is a stock constraint attached to portfolio choice. There is also a flow constraint, that the net amount of assets accumulated (liabilities issued) by one sector must equal its net savings (expenditures). The Tobinian macroeconomic portfolio approach characterizes the potential for financial market instability, focusing on the interconnectedness of all three markets. The paper goes on to study the potential for labour market and fiscal policies to stabilize unstable macroeconomies.

In the last months, the world's economies were confronted with the largest economic recession since the Great Depression. The occurrence of a worldwide financial market meltdown as a consequence originally stemming from of the crisis in the US subprime housing sector was only prevented by extraordinary monetary and fiscal policy measures implemented at the international level. Although the world economy seems now to be slowing recovering, it is worthwhile exploring the fragility and potentially destabilizing feedbacks of advanced macroeconomies in the context of Keynesian macro models. Fragilities and destabilizing feedback mechanisms are known to be potential features of all markets-the product markets, the labor market, and the financial markets. In this paper we focus in particular on the financial market. We use a Tobin-like macroeconomic portfolio approach, and the interaction of heterogeneous agents on the financial market to characterize the potential instability of the financial markets. Though the study of the latter has been undertaken in many partial models, we focus here on the interconnectedness of all three markets. Furthermore, we also study how labor market, fiscal and monetary policies can stabilize unstable macroeconomies. Besides other stabilizing policies we in particular propose a countercyclical monetary policy that sells assets in the boom and purchases assets in recessions. Modern stability analysis is brought to bear to demonstrate the stabilizing effects of those suggested policies.

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