Model Validation

How accurate is the HMM, really?

We audited our own model the way a skeptic would: refit quarterly using only data available at the time, signals applied the next day, costs included. Across all 20 markets. These are the results — including where the model loses.
The honest test. Most published backtests train a model on the full history and then "predict" that same history — the model has already seen the answers. Here the HMM is refit every quarter (~53 refits per market) using only past data, then classifies the next quarter it has never seen. The day-T signal decides the day-T+1 position, with 0.10% cost per switch. This is called walk-forward validation.
Bear-day vs bull-day volatility
Next-day realized vol on days labelled bear vs days labelled bull, out of sample. This is the model's real skill.
Markets with smaller max drawdown
Stepping to cash in bear regimes cut the worst peak-to-trough loss in most markets.
Markets beating buy & hold on Sharpe
As a return-timing strategy it mostly loses. We publish this anyway — it tells you what the model is for.
Label agreement, honest vs full-history
How often the out-of-sample regime label matches the dashboard's full-history label — a stability check.
What this means for how you use the dashboard. Treat the HMM as a sea-state gauge, not a compass. A bear label reliably means rougher waters ahead — higher volatility, fatter left tail — so it's a signal to size down, hedge, or tighten risk. It is not a reliable signal that prices will fall: in some markets (Nifty included) bear-labelled days actually saw higher average next-day returns, because panic days cluster with rebound days. Vol is forecastable; direction largely isn't.
All 20 markets — walk-forward strategy vs buy & hold

Strategy = long the index unless the regime is bear, then cash at the local risk-free rate, net of costs. Green = strategy beat buy & hold on that metric. Sorted by Sharpe improvement.

Market Strategy CAGR B&H CAGR Strategy Sharpe B&H Sharpe Strategy max DD B&H max DD Bear/bull vol

Market detail

Growth of 100 · out-of-sample window · strategy shown net of 0.10% per switch.

Does today's label predict tomorrow?
Today's regime % of days Next-day vol (ann.) Next-day return Days falling >1%

Strategy behaviour
% time invested
rest in local cash
Switches
index ↔ cash, whole window
Avg regime length
trading days
Label agreement
vs full-history labels
Method, in full. 3-state Gaussian HMM per market on daily log returns, 10-day realized vol, FX change and (where available) implied vol — the same features the live dashboard uses. Initial training window ~3 years, refit every 63 trading days on an expanding window; features are standardised using only the training window. States are labelled bear/neutral/bull by a volatility-dominant score, and probabilities are filtered (causal), never smoothed. See Methodology for the model itself. Results regenerate when we rerun the audit; last run . Not investment advice — see Disclaimer and Terms.