Abstract: A computer implemented method determines a margin requirement for a financial product portfolio. Market conditions for the financial product portfolio are characterized by a zero curve. The method includes producing a plurality of scenario curves, each scenario curve reflecting a principal component analysis (PCA) model of the zero curve with a respective PCA factor of a plurality of PCA factors of the PCA model offset from a corresponding base value for the zero curve, calculating a respective projected value of the financial product portfolio for each scenario curve of the plurality of scenario curves, calculating a loss risk amount for each PCA factor based on the respective projected value and a current value of the financial product portfolio, and determining the margin requirement based on a sum of the loss risk amounts for the plurality of PCA factors.