GOODWILL

The table below details changes in the goodwill balance:



$ in millions	Net Book Value
January 1, 2017	6,129.2
Business combinations	193.3
Foreign exchange	268.2
December 31, 2017	6,590.7

January 1, 2016	6,175.7
Business combinations	135.7
Foreign exchange	(182.2	)
December 31, 2016	6,129.2

The 2017 addition to goodwill consists of $193.3 million related to the preliminary valuation of the acquisition of the European ETF business. The 2016 addition to goodwill consists of $135.7 million related to the the acquisitions of our Indian asset management company and Jemstep.

The 2017 and 2016 annual impairment reviews determined that no impairment existed at the respective review dates. No interim impairment tests were deemed necessary during 2017 or 2016.