The total value of a person's net assets. Wealth may be held in various forms: these include money, shares in companies, debt instruments, land, buildings, intellectual property such as patents and copyrights, and valuables such as works of art. From this any debts owed are subtracted. The valuation put on these assets is liable to uncertainty and fluctuations, as many of the assets are not marketed, and those that are may have volatile market prices. It is disputable whether wealth should include prospective accessions of assets: the actuarial value of pension rights can be calculated, but what pensioners will actually receive depends on how long they survive. Similarly, prospective legacies have incentive effects comparable to actual wealth, but what will actually be received depends on how long testators survive, whether their assets change, and whether they change their minds about how to bequeath them. See also net wealth.