Factor Risk Decomposition is the process of attributing an asset's total risk (volatility) to its exposures to underlying macroeconomic factors. Rather than viewing volatility as a single opaque number, factor models reveal its true composition — how much comes from broad equity market exposure, interest rate sensitivity, currency risk, commodity prices, and other drivers.
StressTest.pro uses a 19-factor model spanning: US equities, developed market equities, emerging market equities, growth/tech, value, small cap, quality, short-term rates, long-term bonds, investment-grade credit, high-yield credit, gold, energy, real estate, cryptocurrency, copper, volatility, USD strength, and inflation. Each factor is represented by a liquid market instrument (e.g. VTI.US for US equities, TLT.US for long-term bonds).
The math behind this is multivariate regression: the daily returns of the asset are regressed against the daily returns of all 19 factor proxies simultaneously. The resulting coefficients (betas) quantify exposure to each factor, and those betas multiplied by factor variances and covariances produce the % contribution to total risk.
Why does this matter? An investor who thinks they are 'diversified' across 10 different tech stocks may find that 85% of their portfolio risk comes from a single factor: the Technology / Growth factor. Factor decomposition makes hidden concentrations visible.