Articles

Notes on rates, financial mathematics, and the code I write to check whether I actually understand them.

Why the term premium stopped explaining the long end

The standard decomposition splits a long yield into expected policy and a term premium. Since 2022 the residual has been doing most of the work — and that is a statement about the model, not about the bond market.

MAR 2026 · 11 min · ratesmacro
Vol surface interpolation in 60 lines

An SVI parameterisation that stays arbitrage-free across strikes, fitted with nothing heavier than scipy.optimize and a careful choice of initial guess.

FEB 2026 · 1 min · pythonoptions
Notes on Itô, slowly

Working through the Itô integral one assumption at a time, without skipping the step where quadratic variation stops behaving like anything in ordinary calculus.

JAN 2026 · 1 min · mathstochastic
Backtesting my own bad ideas

Six strategies I believed in, run against a walk-forward split with realistic costs. Five die on transaction costs alone; the sixth dies more interestingly.

DEC 2025 · 1 min · statspython
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