The changes in the carrying amount of MSRs for the three and six months ended June 30, 2019 and 2018 are as follows (in thousands):

	Three Months Ended June 30,						Six Months Ended June 30,
Mortgage Servicing Rights	2019			2018			2019			2018
Beginning Balance	$	413,004		$	386,953		$	416,131		$	399,349
Additions		21,433			25,342			38,687			31,731
Purchases from an affiliate		424			1,099			722			1,608
Amortization		(21,436	)		(20,011	)		(42,115	)		(39,305	)
Ending Balance	$	413,425		$	393,383		$	413,425		$	393,383

Valuation Allowance
Beginning Balance	$	(6,044	)	$	(5,427	)	$	(4,322	)	$	(6,723	)
Decrease		(6,598	)		4,084			(8,320	)		5,380
Ending Balance	$	(12,642	)	$	(1,343	)	$	(12,642	)	$	(1,343	)
Net balance	$	400,783		$	392,040		$	400,783		$	392,040

Servicing fees are included in “Management services, servicing fees and other” in Newmark’s unaudited condensed consolidated statements of operations and are as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Servicing fees	$	25,977	$	26,092	$	51,608	$	51,224
Escrow interest and placement fees		5,624		3,867		10,987		6,834
Ancillary fees		4,131		2,374		7,315		3,201
Total servicing fees and escrow interest	$	35,732	$	32,333	$	69,910	$	61,259

Newmark’s primary servicing portfolio at June 30, 2019 and December 31, 2018 was approximately $58.1 billion and $57.1 billion, respectively. Also, Newmark is the named special servicer for a number of commercial mortgage-backed securitizations. Upon certain specified events (such as, but not limited to, loan defaults and loans assumptions), the administration of the loan is transferred to Newmark. Newmark’s special servicing portfolio at June 30, 2019 and December 31, 2018 was $2.7 billion and $2.9 billion, respectively.

The estimated fair value of the MSRs at June 30, 2019 and December 31, 2018 was $431.5 million and $451.9 million, respectively.

Fair values are estimated using a valuation model that calculates the present value of the future net servicing cash flows. The cash flows assumptions used are based on assumptions Newmark believes market participants would use to value the portfolio. Significant assumptions include estimates of the cost of servicing per loan, discount rate, earnings rate on escrow deposits and prepayment speeds. The discount rates used in measuring fair value for the six months ended June 30, 2019 and the year ended December 31, 2018 were between 3.0% and 13.5% and varied based on investor type. An increase in discount rate of 100 bps or 200 bps would result in a decrease in fair value by $11.7 million and $22.8 million, respectively, at June 30, 2019 and by $12.4 million and $24.4 million, respectively, at December 31, 2018.