When building a risk model, the total variance (or total risk) of an asset or portfolio is decomposed into systematic (general market) risk and specific (idiosyncratic) risk. Adding more general risk factors to a VaR model typically helps to explain a larger portion of the asset's total variance. As more of the total risk is attributed to these general market factors, the unexplained or residual variance—which constitutes the specific risk—will necessarily decrease. Therefore, increasing the number of general risk factors leads to a decrease in the size of specific risks.