You can request up to a year's worth of historical NAV's for a given fund. If you don't know the Fund Symbol in question you can locate it using the Fund Prices page and then click on the Price History link below the desired fund. Define the date range by either selecting a pre-defined Time Period or define your own From: and To: dates in MM/DD/YYYY format.

Note: NAV's are not returned for dates the market was closed (weekends, holidays, etc...). Daily income factors are returned for money market and bond funds, if applicable.