Eversource maintains trusts that hold marketable securities to fund certain non-qualified executive benefits. These trusts are not subject to regulatory oversight by state or federal agencies. CYAPC and YAEC maintain legally restricted trusts, each of which holds marketable securities, to fund the decommissioning and spent nuclear fuel removal obligations of their nuclear fuel storage facilities.

WMECO maintained a spent nuclear fuel trust to fund WMECO's pre-1983 spent nuclear fuel obligation. In late 2015, this trust was liquidated to satisfy the spent nuclear fuel obligation with the DOE. For further information, see Note 8, "Long-Term Debt."

Trading Securities: Eversource has elected to record certain equity securities as trading securities, with the changes in fair values recorded in Other Income, Net on the statements of income. As of December 31, 2015 and 2014, these securities were classified as Level 1 in the fair value hierarchy and totaled $14.2 million and $85.1 million, respectively. For the years ended December 31, 2015, 2014 and 2013, net gains on these securities of $2 million, $1.9 million and $10.2 million, respectively, were recorded in Other Income, Net on the statements of income. Dividend income is recorded in Other Income, Net when dividends are declared. In 2015, certain of the securities classified as trading securities were sold and the proceeds were re-invested in equity securities designated as available-for-sale securities.

Available-for-Sale Securities: The following is a summary of available-for-sale securities, which are recorded at fair value and are included in current and long-term Marketable Securities on the balance sheets.

		As of December 31,
		2015								2014
				Pre-Tax		Pre-Tax						Pre-Tax		Pre-Tax
		Amortized		Unrealized		Unrealized				Amortized		Unrealized		Unrealized
(Millions of Dollars)		Cost		Gains		Losses		Fair Value		Cost		Gains		Losses		Fair Value
Eversource
	Debt Securities^{(1) (2)}	$	256.5	$	4.5	$	(0.6)	$	260.4	$	313.0	$	7.5	$	(0.3)	$	320.2
	Equity Securities⁽¹⁾		215.3		59.2		(3.4)		271.1		160.6		73.3		-		233.9
WMECO
	Debt Securities⁽²⁾		-		-		-		-		58.2		-		(0.1)		58.1

Unrealized Losses and Other-than-Temporary Impairment: There have been no significant unrealized losses, other-than-temporary impairments or credit losses in 2015 or 2014. Factors considered in determining whether a credit loss exists include the duration and severity of the impairment, adverse conditions specifically affecting the issuer, and the payment history, ratings and rating changes of the security. For asset-backed debt securities, underlying collateral and expected future cash flows are also evaluated.

Realized Gains and Losses: Realized gains and losses on available-for-sale securities are recorded in Other Income, Net for Eversource's benefit trust and are offset in Other Long-Term Liabilities for CYAPC and YAEC. Eversource utilizes the specific identification basis method for the Eversource benefit trust and the average cost basis method for the CYAPC and YAEC nuclear decommissioning trusts to compute the realized gains and losses on the sale of available-for-sale securities.

Contractual Maturities: As of December 31, 2015, the contractual maturities of available-for-sale debt securities were as follows:

Eversource	Amortized		Fair
(Millions of Dollars)	Cost		Value
Less than one year⁽¹⁾	$	33.3	$	33.2
One to five years		50.2		50.7
Six to ten years		56.6		57.2
Greater than ten years		116.4		119.3
Total Debt Securities	$	256.5	$	260.4

(1) Amounts in the Less than one year category include securities in the CYAPC and YAEC nuclear decommissioning trusts, which are restricted and are classified in long-term Marketable Securities on the balance sheets.

Fair Value Measurements: The following table presents the marketable securities recorded at fair value on a recurring basis by the level in which they are classified within the fair value hierarchy:

Eversource		As of December 31,
(Millions of Dollars)		2015		2014
Level 1:
	Mutual Funds and Equities	$	285.3	$	319.0
	Money Market Funds		26.9		24.9
Total Level 1		$	312.2	$	343.9
Level 2:
	U.S. Government Issued Debt Securities (Agency and Treasury)	$	46.6	$	51.3
	Corporate Debt Securities		43.9		49.1
	Asset-Backed Debt Securities		20.0		54.1
	Municipal Bonds		111.4		116.3
	Other Fixed Income Securities		11.6		24.5
Total Level 2		$	233.5	$	295.3
Total Marketable Securities		$	545.7	$	639.2

As of December 31, 2014, the WMECO spent nuclear fuel trust included investments in money market funds of $4.3 million classified as Level 1 in the fair value hierarchy, and $14.7 million of corporate debt securities, $14.5 million of asset-backed debt securities, $13 million of municipal bonds and $11.6 million of other fixed income securities classified as Level 2 in the fair value hierarchy. The trust was liquidated in late 2015.

U.S. government issued debt securities are valued using market approaches that incorporate transactions for the same or similar bonds and adjustments for yields and maturity dates. Corporate debt securities are valued using a market approach, utilizing recent trades of the same or similar instrument and also incorporating yield curves, credit spreads and specific bond terms and conditions. Asset-backed debt securities include collateralized mortgage obligations, commercial mortgage backed securities, and securities collateralized by auto loans, credit card loans or receivables. Asset-backed debt securities are valued using recent trades of similar instruments, prepayment assumptions, yield curves, issuance and maturity dates, and tranche information. Municipal bonds are valued using a market approach that incorporates reported trades and benchmark yields. Other fixed income securities are valued using pricing models, quoted prices of securities with similar characteristics, and discounted cash flows.