March 29, 1900, is considered by many to be the day mathematical finance was born. On that day a French doctoral student, Louis Bachelier, successfully defended his thesis Théorie de la Spéculation at the Sorbonne. The jury, while noting that the topic was "far away from those usually...

Biographical note: Mark Davis, Professor of Mathematics at Imperial College London, has written three books on stochastic modeling and control, most recently "Markov Models and Optimization". Alison Etheridge, Professor of Probability at the University of Oxford, is the author of "A Course in...