Answer: Fundriver's default setting for rolling average of the fund uses the average of the history available. This can be set up to average annually, quarterly, or monthly. So if a new endowment is set up for $1,000,000, for example, the average starts with the gift date and moves forward.
This setting can be changed, though, to look at the full 3 years, including zero balances in each period and thereby reducing the amount of the spending calculation. This would require a customization to the client's database.
Most Fundriver clients use the default setting, but we do have some that want to average using the full 3 years. Also, the majority of clients set up their rule as a percent average of the fund using quarterly figures for averaging.