What valuation method provides the fair value of investments at any time?

The method that provides the fair value of investments at any time is marked to market valuation. This approach involves adjusting the value of an asset to reflect its current market price, allowing for real-time assessment of an investment's worth. This is particularly important for variable investments such as stocks or other securities, where market prices fluctuate frequently. By using this method, investors can get a more accurate and updated picture of their portfolio's value, enhancing transparency and decision-making.

In contrast, estimated cost valuation relies on previous estimates or inputs rather than current market conditions, which may not accurately reflect the actual value at a given moment. Historical cost valuation records the initial purchase price of an asset, failing to take into account subsequent fluctuations in the market, thus potentially misrepresenting an asset's current worth. Accrual valuation focuses on recognizing revenue and expenses when they are earned or incurred, rather than when cash is exchanged, which does not directly pertain to the valuation of investments in terms of their fair market value.