Public pension plans are probably the largest financial transaction systems that we have. In OECD countries their expenditure ranges from 5 to 15 percent, and their liabilities, as a rough estimate, from 150 to 300 percent of gross domestic product (GDP). For many governments, pension payments are the single largest expenditure. National pension plans also represent one of the most long-term commitments of governments. The size of these systems is of course reflected in their importance to insured citizens. For many, perhaps most, the claim of individuals on the public pension system represents their single largest “asset”.