The last 10 years have witnessed very signi cant changes in nance, both as an
academic subject and as a professional eld. Finance is becoming an empirical (rather
than axiomatic) science; correspondingly, nancial engineers (quants) have an increasingly
important role to play in the nancial industry. There are various reasons for
this change, but the most important must surely be the availability of data, and the
possibility to access and process this data very quickly. Fifteen years ago, it was not
so easy to nd data, even on the most liquid markets. Now, one has direct access to
high-frequency data (on the scale of seconds) not only for stocks, currencies or interest
rates, but also for more exotic markets such as option markets, energy markets,
weather derivatives, etc.