The underlying assets giving value to a company, investment or loan. The asset base is not fixed, it will appreciate or depreciate according to market forces. Lenders use physical assets as a guarantee that at least a portion of money lent can be recouped through the sale of the backed asset in the case that the loan itself cannot be repaid. Taobiz explains Asset Base The value of a home might increase or decrease over time, affecting the underlying collateral in a mortgage. Similarly, the price of a commodity used as the asset base of derivative can also increase or decrease rapidly, changing the price that investors are willing to pay for it. Examples of asset bases include a home (for a mortgage) and factory equipment (business loan). A derivative would "derive" its value from an underlying asset.