Brownian Motion Quant Interview Basics
Brownian motion quant interview basics for continuous random paths, independent increments, variance scaling, finance use, and caveats.
Candidates preparing for continuous-time models and options basics.
Brownian motion is a continuous-time random process
Brownian motion has continuous paths, independent increments, and normally distributed changes with variance proportional to elapsed time under the standard model.
Variance scales with time
Over a longer interval, Brownian uncertainty grows with time in variance and with square root of time in standard deviation. That scaling appears in options and diffusion intuition.
Concrete example
If a model uses Brownian motion for a price driver, the one-day standard deviation scales differently from the four-day standard deviation by roughly a square-root relationship.
Finance uses it as an idealization
Black-Scholes-style models use Brownian assumptions for tractability. Real markets can have jumps, changing volatility, discrete trading, and heavy tails.
Common mistakes
Candidates often treat Brownian motion as a literal market description. In interviews, explain the useful approximation and what market features it ignores.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.