Hi everybody (financial journalists I'm looking at you!), it would be super if you'd stop describing five or ten standard deviation events as events that "can never happen according to quantitative models". Clickbait.

Markets are very fat-tailed. They're even more fat-tailed these days due to broken liquidity conditions. Moves that are many times the unconditional standard deviation of historical moves happen constantly in some market or another. Its all very exciting of course.

Please stop talking about normal distributions. Nobody cares. The normal distribution is a thing of mathematical elegance and beauty created for the convenience of its properties, and because of some neat results like the law of large numbers and the central limit theorem.

And stop saying "options markets assume normal distributions because they use Black-Scholes". FFS people. The entire premise of a volatility surface (differences in IV by skew and maturity) is that markets are very non-normally distributed.

Black-Scholes itself is an accounting convention, not a 'model' of how things work. BLS implied volatility is a convenient transformation of option prices into a standardized format that allows easier comparison across strikes, maturities and underlyings.