Discrete-time models fail
at the moment risk management
matters most.
Inside the Stokhos Labs Fin-Tech division, we apply the studio's AI engineering depth to one narrow problem: institutional risk models that underperform in non-stationary regimes. In moments of financial panic, that structural gap becomes catastrophic.
Three structural flaws
embedded in every discrete model.
ARX-GARCH updates once per day. During a liquidity crisis, conditions shift in minutes, leaving stale data at exactly the wrong moment.
GARCH variance is a backward-looking average of past squared errors. Under fat-tailed, regime-switching distributions (standard in crises), the Gaussian assumption produces systematically miscalibrated uncertainty estimates.
When a shock arrives, discrete models require recalibration that takes hours or days. By then, positions have moved. A model that updates after the fact is a postmortem tool, not a risk tool.
The assumption that breaks
under market stress.
Discrete-time GARCH
εt = σt zt, zt ~ N(0,1)
σt2 = ω + αεt−12 + βσt−12
Updates once per period. Gaussian noise hardcoded. Variance is a backward-looking average with no mechanism to incorporate intra-period shocks.
Neural SDE (Stokhos)
+ gφ(Y(t), t) dW(t)
Evolves continuously. Diffusion gφ is conditioned on the current state, so uncertainty widens automatically in stressed regimes. No Gaussian constraint.
Discrete-time models suffer from adaptive latency: the structural delay between when a regime shift occurs and when the model detects it. GARCH variance requires a sequence of large shocks to recalibrate; by the time it registers the new regime, the crisis has already peaked. This isn't a calibration problem. It's a mathematical architecture problem.
Beginning March 9, 2020, U.S. Treasury yields dislocated sharply; the 10-year moved more than 50 basis points in a week, bid-ask spreads blew out, and the Fed intervened with emergency purchases. ARX-GARCH, trained on the preceding calm, extrapolated linear trends into a nonlinear regime collapse. Its confidence interval expanded symmetrically but offered no directional signal.
What institutional risk teams
need but don't have.
- Daily-recalibrated GARCH with stale intra-day parameters
- Gaussian VaR that underestimates tail risk in crises
- Rigid linear factor structure in term structure models
- Post-hoc stress tests that describe past crises, not future ones
- Continuous-time model that updates as new data arrives
- State-dependent uncertainty: crisis regimes widen automatically
- Neural drift + diffusion with no distributional assumptions
- 64.3% MSE reduction on the hardest out-of-sample stress test available
See the solution.
Drift networks, diffusion networks, Euler-Maruyama integration, and the results behind the Fin-Tech division.