A FMV should be used when the party has an obligation to comply with US GAAP or IFRS, or when the application of the data requires an executable market price such as when striking NAV, (Net Asset Value), performing financial reporting, tax compliance, or as a best practice when creating indices. Indices may choose to use a FMV as a best practice because it is compatible with how fund assets are valued and because an actual executable price is tradable for hedging purposes.