Goodwill. As of June 30, 2019 and December 31, 2018, the carrying value of goodwill totaled $31.2 million and $412,000, respectively. The Company recorded additional goodwill of $30.8 million related to the Optima merger during the second quarter of 2019. Goodwill is tested for impairment, based on its fair value, at least annually. As of June 30, 2019 and December 31, 2018, no goodwill impairment has been recognized.

Core deposit intangibles. During the second quarter of 2019, the Company recorded an asset for core deposit intangibles (“CDI”) of $3.6 million related to the Optima merger. Amortization of CDI assets totaled $90,000 for the three and six months ended June 30, 2019. As of June 30, 2019, the carrying value of CDI assets totaled $3.5 million. The weighted-average amortization period for CDI was approximately ten years at June 30, 2019.

Mortgage servicing rights. Periodically, the Company sells certain residential mortgage loans to the secondary market. Generally, these loans are sold without recourse or other credit enhancements. As of June 30, 2019, loans held for sale totaled $384,000. The Company did not have any loans held for sale at and December 31, 2018.

The Company sells loans and either releases or retains the servicing rights. For loans sold with servicing rights retained, we provide the servicing for the loans on a per-loan fee basis. Mortgage loans sold and servicing rights retained during the period ended June 30, 2019 and the year ended December 31, 2018 were $867,000 and $1.6 million, respectively. Total gain on loans held for sale were $15,000 and $18,000, for the three months ended June 30, 2019 and June 30, 2018, respectively. Total gain on loans held for sale were $31,000 and $45,000, for the six months ended June 30, 2019 and June 30, 2018, respectively.

An analysis of mortgage servicing rights, which are included in other assets, follows:

	Mortgage Servicing Rights			Valuation Allowance			Total
	(dollars in thousands)
Balance at December 31, 2017	$	823		$	(30	)	$	793
Mortgage servicing rights capitalized		5			—			5
Amortization charged against servicing income		(70	)		—			(70	)
Change in impairment reserve		(30	)		30			—
Balance at June 30, 2018	$	728		$	—		$	728

Balance at December 31, 2018	$	666		$	—		$	666
Mortgage servicing rights acquired as a result of the merger		334			—			334
Mortgage servicing rights capitalized		7			—			7
Amortization charged against servicing income		(106	)		—			(106	)
Change in impairment reserve		—			(10	)		(10	)
Balance at June 30, 2019	$	901		$	(10	)	$	891

The fair value of our mortgage servicing rights (“MSR”) portfolio was $1.1 million and $1.0 million as of June 30, 2019 and June 30, 2018, respectively. The fair value of mortgage servicing rights is estimated based on the present value of expected cash flows, incorporating assumptions for discount rate, prepayment speed, and servicing cost.

The weighted-average amortization period for the mortgage servicing rights portfolio was 6.0 years and 7.5 years at June 30, 2019 and December 31, 2018, respectively.

The estimated aggregate future amortization expense for mortgage servicing rights for each of the next five years and thereafter is as follows:

	Future Amortization Expense
	(dollars in thousands)
Remainder of 2019	$	74
2020		133
2021		113
2022		96
2023		81
Thereafter		404
Total	$	901