In April 2015, the Company entered into an Agreement and Plan of Reorganization with Renzu, Inc. (“Renzu”) and various other parties. Renzu’s business consisted of developing mobile measurement and analytics offerings, which assisted the Company in gathering implicit data within the mobile market. The Company, via merger, purchased all of the outstanding shares of Renzu on the closing date of May 20, 2015. The acquisition qualified as a business combination and was accounted for accordingly.

The total purchase price of $17.0 million was comprised of the issuance of restricted common stock of $10.3 million and cash payment of $6.7 million. The Company recorded $0.7 million of net tangible liabilities, $5.5 million of identifiable intangible assets based on their estimated fair values and $12.2 million of residual goodwill. Goodwill resulted primarily from the Company’s expectations of synergies from the integration of Renzu’s employee base and product offerings with the Company’s product offerings. Goodwill was not deductible for tax purposes.

Upon acquisition in May 2015, the Company’s intention was to integrate Renzu’s mobile measurement and analytics product into the existing core business, should the resulting product be successful. After releasing the product and evaluating its performance, the Company determined that the mobile measurement and analytics product was not a strategic fit for its other products and determined that it would focus on key investments that were more tightly tied with its core business. In its evaluation, the Company concluded Renzu was a standalone entity that was not fully integrated into the Company’s existing business lines and where the Company did not benefit from the acquired goodwill. In November 2016, the Company implemented a plan to wind down the operations of Renzu, as the acquisition was not integrated into the Company’s business, and derecognized the carrying value of goodwill and intangibles of $12.2 million and $3.7 million, respectively, which is included in restructuring within the consolidated statements of operations (see Notes 2 and 13 for additional discussion).

In July 2015, the Company entered into an Agreement and Plan of Reorganization with TechValidate Software, Inc. (“TechValidate”) and various other parties. TechValidate is an online software platform specializing in marketing content automation. The Company, via merger, purchased all of the outstanding shares of TechValidate, then merged TechValidate with and into SurveyMonkey Inc. on the close date of July 31, 2015. The acquisition qualified as a business combination and was accounted for accordingly.

The total purchase price of $60.4 million was comprised of the issuance of common stock of $23.8 million and cash payment of $36.6 million (of which $22.2 million was paid at close and $14.4 million was deferred and paid in August 2016). The Company recorded $5.8 million of net tangible liabilities, $15.8 million of identifiable intangible assets based on their estimated fair values and $50.4 million of residual goodwill. Goodwill resulted primarily from the Company’s expectations of synergies from the integration of TechValidate’s employee base and product offerings with the Company’s product offerings. Goodwill was not deductible for tax purposes.

As of December 31, 2018 and 2017, capitalized internal-use software consisted of the following:

(in thousands)	December 31, 2018			December 31, 2017
Gross capitalized internal-use software	$	109,133		$	95,607
Less: Accumulated amortization		(75,853	)		(54,114	)
Capitalized internal use software, net	$	33,280		$	41,493

Amortization expense related to capitalized internal-use software was $21.7 million, $21.1 million and $19.4 million during the years ended December 31, 2018, 2017 and 2016, respectively, and is included in cost of revenue in the consolidated statements of operations.

As of December 31, 2018 and 2017, intangible assets, net consisted of the following:

	December 31, 2018							December 31, 2017
(in thousands)	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Customer relationships	$	47,696	$	(42,410	)	$	5,286	$	47,696	$	(40,696	)	$	7,000
Trade name		6,072		(5,796	)		276		6,072		(5,192	)		880
Technology		22,007		(18,245	)		3,762		22,007		(16,293	)		5,714
Acquisition intangible assets, net	$	75,775	$	(66,451	)	$	9,324	$	75,775	$	(62,181	)	$	13,594

Amortization expense was $4.3 million, $4.5 million and $8.8 million during the years ended December 31, 2018, 2017 and 2016, respectively.

As of December 31, 2018, future amortization expense by year is expected to be as follows:

(in thousands)	Capitalized internal-use software, net		Acquisition intangible assets, net
2019	$	12,662	$	3,839
2020		5,925		2,952
2021		1,092		1,705
2022		—		828
Total amortization expense	$	19,679	$	9,324

Future capitalized internal-use software amortization excludes $13.6 million of costs which are currently in the development phase.

The changes in the carrying amount of goodwill, net were as follows (in thousands):