. Goodwill and acquired intangible assets

The Company has

one

reporting unit and goodwill represents the synergies realized in its acquisitions of Imugen, Inc., or Imugen, and Immunetics, Inc., or Immunetics. The carrying amount of goodwill reflected in the Company’s condensed consolidated balance sheets was

$2.5

million at

September 30, 2018

and

December 31, 2017.

In conjunction with the Transaction (see Note

14.

Discontinued operations

) and pursuant to ASC

350

51,

the Company allocated a portion of the goodwill to the business being disposed of based on the relative fair value method. As a result, goodwill of

$1.5

million was allocated to assets held for sale.

Acquired intangible assets consisted of the following as of

September 30, 2018

and

December 31, 2017:

	As of September 30 , 201 8
(in thousands)	Amortization period (years)				Gross carrying amount		Accumulated Amortization		Net carrying amount
Immunetics technology - clinical			15		$	883	$	116	$	767
Immunetics customer relationships			11			130		23		107
Immunetics trade name			5			30		12		18
Other		5	-	10		667		601		66
Total					$	1,710	$	752	$	958

	As of December 31, 20 17
(in thousands)	Amortization period (years)				Gross carrying amount		Accumulated Amortization		Net carrying amount
Immunetics technology - clinical			15		$	883	$	72	$	811
Immunetics customer relationships			11			130		14		116
Immunetics trade name			5			30		8		22
Other		5	-	10		692		605		87
Total					$	1,735	$	699	$	1,036

The weighted average amortization period of our definite-lived intangible assets is

years. Amortization expense related to acquired intangible assets is estimated at

$0.1

million per year for each of the years

2019

through

2023.