INVESTMENTS

Available for Sale Securities

Our available for sale securities are reported in Prepaid expenses and other current assets. Unrealized investment gains (losses) on available for sale securities were as follows (in millions):



	Year Ended				Six Months Ended
	December 31, 2017		December 31, 2016		December 31, 2015
Equity securities, at cost less impairments	$	15.5	$	16.5	$	6.4
Gross unrealized gains	1.5		21.7		9.3
Gross unrealized losses	—		—		(0.8		)
Estimated fair value of equity securities	$	17.0	$	38.2	$	14.9

The factors affecting the assessment of impairments include both general financial market conditions and factors specific to a particular company. We recorded impairment charges of $1.8 million and $10.7 million during the year ended December 31, 2016, and the six months ended December 31, 2015, respectively, related to other-than-temporary impairments of marketable equity securities due to prolonged losses incurred on each of the investments.

We have evaluated the near-term prospects of the equity securities in relation to the severity and duration of any impairments, and based on that evaluation, we have the ability and intent to hold these investments until a recovery of fair value.

We sold a number of our investment securities and recorded gains of $1.6 million and $1.0 million during the years ended December 31, 2017 and December 31, 2016, respectively. The gains were reclassified out of AOCI and into earnings.

Cost Method Investments

Our cost method investments totaled $6.3 million, $6.9 million, and $6.9 million at December 31, 2017, December 31, 2016, and December 31, 2015, respectively, and were included in Other non-current assets. During the year ended December 31, 2017, due to significant and prolonged losses incurred by one of our cost method investments, we recorded a $1.0 million impairment charge in Other (income) expense, net on the Consolidated Statements of Operations.

Equity Method Investments

Our equity method investments totaled $4.9 million, $4.6 million, and $45.5 million at December 31, 2017, December 31, 2016, and December 31, 2015, respectively, and were included in Other non-current assets. We recorded net gains of $0.3 million, and net losses of $4.1 million, $5.4 million, and $11.6 million during the years ended December 31, 2017 and December 31, 2016, the six months ended December 31, 2015, and the year ended June 27, 2015, respectively, for our proportionate share of the equity method investment earnings or losses. The gains and losses were recorded in Other (income) expense, net on the Consolidated Statements of Operations.

During the year ended December 31, 2016, one of our equity method investments became publicly traded. As a result, we transferred the $15.5 million investment to available for sale and recorded an $8.7 million unrealized gain, net of tax in Other Comprehensive Income ("OCI"). In addition, due to significant and prolonged losses incurred on one of our equity method investments, we recorded a $22.3 million impairment charge in Other (income) expense, net on the Consolidated Statements of Operations.