(1)	Principally reflects changes in pricing spread, annual total prepayment speed, per loan annual cost of servicing and UPB of underlying loan inputs.

(2)	Represents changes due to realization of cash flows.

Mortgage Servicing Liabilities Carried at Fair Value:

The activity in MSLs carried at fair value is summarized below:


	Year ended December 31,
	2022		2021		2020

	(in thousands)
Balance at beginning of year	$	2,816	$	45,324	$	29,140
Mortgage servicing liabilities resulting from loan sales		—		106,631		23,325
Changes in fair value due to:
Changes in inputs used in valuation model (1)		(347)		(68,020)		31,757
Other changes in fair value (2)		(373)		(81,119)		(38,898)
Total change in fair value		(720)		(149,139)		(7,141)
Balance at end of period	$	2,096	$	2,816	$	45,324
Unpaid principal balance of underlying loans at end of year	$	33,157	$	60,593	$	2,857,492

(1)

During the year ended December 31, 2021, significant changes were made to valuation inputs used to estimate the fair value of MSLs in recognition of the observed increase in the proportion of performing government insured or guaranteed loans and reduced expected costs and losses from defaulted government insured or guaranteed loans underlying the Company’s MSLs.

(2)	Represents changes due to realization of cash flows.

Contractual servicing fees relating to MSRs and MSLs are recorded in Net loan servicing fees—Loan servicing fees—From non-affiliates on the consolidated statements of income; late charges and other ancillary fees relating to MSRs and MSLs are recorded in Net loan servicing fees—Loan servicing fees—Other on the Company’s consolidated statements of income. Such amounts are summarized below:


	Year ended December 31,
	2022		2021		2020

	(in thousands)
Contractual servicing fees	$	1,054,828	$	875,570	$	814,646
Other fees:
Late charges		40,583		29,848		36,339
Other		13,742		29,505		25,543
	$	1,109,153	$	934,923	$	876,528