There is provided a computer-implemented method of estimating a capital reserve requirement to cover the longevity risk exposure of a financial instrument in the case of a future longevity shock, the financial instrument undertaking to pay to an investor sums according to a payment schedule of amounts arranged to match with the future cash flow obligations of a pension scheme to at least a portion of its members. The method comprises: (a) calculating, using computing apparatus, an expected payment schedule of the financial instrument by calculating what the cash flow obligations of the pension scheme to its relevant members would be in the case of an expected longevity scenario for the pension scheme membership occurring; (b) calculating, using computing apparatus, a present value of the financial instrument in the case of a stressed longevity scenario for the pension scheme membership in which a longevity-related shock to the expected longevity scenario of the pension scheme membership occurs; and (c) calculating, using computing apparatus and using the calculations of the expected payment schedule and a present value of the financial instrument in the case of a stressed longevity scenario, an estimate of the longevity capital reserve required to ensure that the future cash flow obligations of the financial instrument would be covered in the event that the stressed longevity scenario were to occur.