Normal operational cash flow volatility. Historical company data would be the most appropriate sources to use for the analysis. For example, weekly historical data of net cash flow (benefit outgo + expense – premium income for an insurance company) can be used to fit to a distribution. The 99.5th percentile can be calculated either from historical data directly or from fitted distribution. Distribution fitting may better capture tail events when the history of available experience data is not long enough.36 The historical data should be adjusted to exclude the period when a credit rating downgrade occurred and/or when there was a sharp increase in the interest rate as those two factors are assessed separately from cash flow volatility.