We present a self-consistent model for explosive financial bubbles, which combines a mean-reverting volatility process and a stochastic conditional return which reflects nonlinear positive feedbacks and continuous updates of the investors' beliefs and sentiments. The conditional expected returns...

By combining (i) the economic theory of rational expectation bubbles, (ii) behavioral finance on imitation and herding of investors and traders and (iii) the mathematical and statistical physics of bifurcations and phase transitions, the logperiodic power law (LPPL) model has been developed as a...

Following Levy and Roll [2010], we posit that the market portfolio is the efficient tangent Markowitz portfolio, i.e., it is mean-variance efficient. We then reverse engineer the expected returns and variance terms with constraints imposed by empirical data on a hierarchy of asset baskets. This...

We present a careful analysis of possible issues of the application of the self-excited Hawkes process to high-frequency financial data and carefully analyze a set of effects that lead to significant biases in the estimation of the "criticality index'' n that quantifies the degree of endogeneity...

Why do investors keep buying underperforming mutual funds? To address this issue, we develop a one-period principal-agent model with a representative investor and a fund manager in an asymmetric information framework. This model shows that the investors perception of the fund plays the key role...

We introduce a new measure of activity of financial markets that provides a direct access to their level of endogeneity. This measure quantifies how much of price changes are due to endogenous feedback processes, as opposed to exogenous news. For this, we calibrate the self-excited conditional...

We propose a reduced form model for the Minskian dynamics of liquidity and of asset prices in terms of the so-called financial accelerator mechanism. In a nutshell, credit creation is driven by the market value of the financial assets employed as collateral in the bank loans. This leads to a...

Krugman (1991)'s target zone model has become the reference of a large part of this literature. Despite its simplicity and elegance, empirical evidence has been lacking. Deriving from Krugman's model analytical expressions for the conditional volatility and density distribution close to the...