Advisors Assistant maintains a Pool Factor which represents the percentage of assets left in a depreciating asset pool, such as a GNMA security.  It is received in downloads and is not normally maintained by individual users.

You can maintain the Pool Factor as long as the Depreciating Asset Pool check box is checked in the Modify Security Information Screen.

The Pool Factor is used to calculate the market value.  Shares x (Price x Pool Factor) = Market Value.

For example, if the Pool Factor is .8745, it means that 87.45% of the pool of investments still exists.  The price is always quoted as if 100% of the pool exists, so the price must be "factored down" to accommodate the fact that the pool is smaller.

If there is a Price Factor involved in the pricing, then the Market Value = Shares x Price x Price Factor x Pool Factor.