5. Mortgage Banking and Servicing Rights

Mortgage banking activities primarily include residential mortgage originations and servicing. As discussed in note 1 above, mortgage servicing rights ("MSRs") are carried at fair market value. The fair value is determined quarterly based on an independent third-party valuation using a discounted cash flow analysis and calculated using a computer pricing model. The system used in this evaluation, Compass Point, attempts to quantify loan level idiosyncratic risk by calculating a risk derived value. As a result, each loan's unique characteristics determine the valuation assumptions ascribed to that loan. Additionally, the computer valuation is based on key economic assumptions including the prepayment speeds of the underlying loans generated using the Andrew Davidson Prepayment Model, FHLMC/FNMA guidelines, the weighted-average life of the loan, the discount rate, the weighted-average coupon, and the weighted-average default rate, as applicable. Along with the gains received from the sale of loans, fees are received for servicing loans. These fees include late fees, which are recorded in interest income, and ancillary fees and monthly servicing fees, which are recorded in noninterest income. Costs of servicing loans are charged to expense as incurred. Changes in fair market value of the MSRs are reported as an increase or decrease to mortgage banking income.

The following table presents the components of mortgage banking income:

(in thousands) Year Ended December 31	2015			2014			2013
Net gain on sale of loans held for sale	$	1,978		$	1,468		$	3,098
Net loan servicing income (expense)
Servicing fees		1,197			1,129			1,121
Late fees		88			112			98
Ancillary fees		212			149			368
Fair value adjustments		(289	)		(830	)		206
Net loan servicing income		1,208			560			1,793
Mortgage banking income	$	3,186		$	2,028		$	4,891

Mortgage loans serviced for others are not included in the accompanying balance sheets. Loans serviced for the benefit of others (primarily FHLMC) totaled $458 million, $441 million, and $456 million at December 31, 2015, 2014 and 2013, respectively. Servicing loans for others generally consists of collecting mortgage payments, maintaining escrow accounts, disbursing payments to investors, and processing foreclosures. Custodial escrow balances maintained in connection with the foregoing loan servicing, and included in demand deposits, were approximately $986 thousand, $888 thousand, and $855 thousand at December 31, 2015, 2014, and 2013, respectively.

Activity for capitalized mortgage servicing rights using the fair value method is as follows:

(in thousands)	2015			2014			2013
Fair value of MSRs, beginning of period	$	2,968		$	3,424		$	2,364
New servicing assets created		557			374			854
Change in fair value during the period due to:
Time decay (1)		(168	)		(162	)		(159	)
Payoffs (2)		(247	)		(202	)		(423	)
Changes in valuation inputs or assumptions (3)		126			(466	)		788
Fair value of MSRs, end of period	$	3,236		$	2,968		$	3,424

(1)	Represents decrease in value due to regularly scheduled loan principal payments and partial loan paydowns.

(2)	Represents decrease in value due to loans that paid off during the period.

(3)	Represents change in value resulting from market-driven changes in interest rates.

The fair values of capitalized mortgage servicing rights were $3.2 million, $3.0 million, and $3.4 million at December 31, 2015, 2014, and 2013, respectively. Fair values for the years ended December 31, 2015, 2014, and 2013 were determined by third-party valuations using a discount rate of 10.1%, 10.1%, and 10.0%, respectively, and weighted average default rates of 2.64%, 3.61%, and 3.36%, respectively. Prepayment speeds generated using the Andrew Davidson Prepayment Model averaged 10.0%, 11.3%, and 9.7% at December 31, 2015, 2014, and 2013, respectively. MSR values are very sensitive to movement in interest rates as expected future net servicing income depends on the projected balance of the underlying loans, which can be greatly impacted by the level of prepayments. CTBI does not currently hedge against changes in the fair value of its MSR portfolio.