Financial bubbles are subject to debate and controversy. However, they are not well understood and are hardly ever characterised specifically, especially ex ante. We define a bubble as a period of unsustainable growth, when the price of an asset increases ever more quickly, in a series of...

We present a plausible micro-founded model for the previously postulated power law finite time singular form of the crash hazard rate in the Johansen-Ledoit-Sornette model of rational expectation bubbles. The model is based on a percolation picture of the network of traders and the concept that...

Building on the notion that bubbles are transient self-fulfilling prophecies created by positive feedback mechanisms, we construct the simplest continuous price process whose expected returns and volatility are functions of momentum only. The momentum itself is measured by a simple continuous...