We introduce the concept of “negative bubbles” as the mirror image of standard financial bubbles, in which positive feedback mechanisms may lead to transient accelerating price falls. To model these negative bubbles, we adapt the Johansen-Ledoit-Sornette (JLS) model of rational expectation...

Hedge funds significantly reduced their equity holdings during the recent financial crisis. In 2008Q3-Q4, hedge funds sold about 29% of their aggregate portfolio. Redemptions and margin calls were the primary drivers of selloffs. Consistent with forced deleveraging, the selloffs took place in...

Recent literature suggests that trading by institutional investors may affect the first and second moments of returns. Elaborating on this intuition, we conjecture that arbitrageurs can propagate liquidity shocks between related markets. The paper provides evidence in this direction by studying...

Large institutional investors own an increasing share of equity markets in the U.S. The implications of this development for financial markets are still unclear. The paper presents novel empirical evidence that ownership by large institutions predicts higher volatility and greater noise in stock...

We present an extension of the Johansen-Ledoit-Sornette (JLS) model to include an additional pricing factor called the Zipf factorʺ, which describes the diversification risk of the stock market portfolio. Keeping all the dynamical characteristics of a bubble described in the JLS model, the new...

The Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles with finite-time singular crash hazard rates has been developed to describe the dynamics of financial bubbles and crashes. It has been applied successfully to a large variety of financial bubbles in many different markets....