8. Mortgage Servicing Assets

We originate and periodically sell commercial mortgage loans but continue to service those loans for the buyers. We also may purchase the right to service commercial mortgage loans for other lenders. A servicing asset is recorded if we purchase or retain the right to service loans in exchange for servicing fees that exceed the going market rate. Changes in the carrying amount of mortgage servicing assets are summarized as follows:


	Nine months ended September 30,
in millions	2012		2011

Balance at beginning of period	$	173	$	196
Servicing retained from loan sales		30		15
Purchases		31		7
Amortization		(43)		(41)
Impairments		(3)		—

Balance at end of period	$	188	$	177


Fair value at end of period	$	237	$	260

The fair value of mortgage servicing assets is determined by calculating the present value of future cash flows associated with servicing the loans. This calculation uses a number of assumptions that are based on current market conditions. The primary economic assumptions used to measure the fair value of our mortgage servicing assets at September 30, 2012, and 2011, generally are:

¿	prepayment speed at an annual rate of 0.00% to 25.00%;

¿	expected credit losses at a static rate of 1.00% to 3.00%;

¿	residual cash flows discount rate of 7.00% to 15.00%; and

¿	value assigned to escrow funds at an interest rate of .27% to 2.78%.

If these economic assumptions change or prove incorrect, the fair value of mortgage servicing assets may as a result change in the future. The volume of loans serviced, expected credit losses, and the value assigned to escrow deposits are critical to the valuation of servicing assets. At September 30, 2012, a 1.00% decrease in the value assigned to the escrow deposits would cause a $33 million decrease in the fair value of our mortgage servicing assets. An increase in the assumed default rate of commercial mortgage loans of 1.00% would cause a $2 million decrease in the fair value of our mortgage servicing assets.

Contractual fee income from servicing commercial mortgage loans totaled $67 million for the nine-month period ended September 30, 2012, and $72 million for the nine-month period ended September 30, 2011. We have elected to account for servicing assets using the amortization method. The amortization of servicing assets is determined in proportion to, and over the period of, the estimated net servicing income. The amortization of servicing assets for each period, as shown in the preceding table, is recorded as a reduction to fee income. Both the contractual fee income and the amortization are recorded in “other income” on the income statement.

Subsequent to its January 19, 2011, publicly issued announcement, Moody’s, a credit rating agency that rates KeyCorp and KeyBank debt securities, indicated to KeyBank that certain escrow deposits associated with our mortgage servicing operations had to be moved to another financial institution that meets Moody’s minimum ratings threshold. As a result of this decision by Moody’s, during the first quarter of 2011, KeyBank transferred approximately $1.5 billion of these escrow deposit balances to an acceptably-rated institution resulting in an immaterial impairment of the related mortgage servicing assets. We funded this movement of the escrow deposits by selling a similar amount of securities available for sale at the time of the transfer. KeyBank had ample liquidity reserves to offset the loss of these deposits.

Additional information pertaining to the accounting for mortgage and other servicing assets is included in Note 1 (“Summary of Significant Accounting Policies”) under the heading “Servicing Assets” on page 119 of our 2011 Annual Report on Form 10-K and Note 11 (“Acquisitions and Discontinued Operations”) under the heading “Education lending” in this report.