The Company elects to record mutual funds purchased by the NU supplemental benefit trust at fair value. As such, any change in fair value of these purchased equity securities is reflected in Net Income. These equity securities, classified as Level 1 in the fair value hierarchy, totaled $37.3 million and $42.2 million as of September 30, 2011 and December 31, 2010, respectively, and are included in current Marketable Securities. Losses on these securities of $7.1 million and $4.9 million for the three and nine months ended September 30, 2011 and gains of $5.7 million and $3.2 million for the three and nine months ended September 30, 2010, respectively, were recorded in Other Income, Net on the accompanying unaudited condensed consolidated statements of income. Dividend income is recorded when dividends are declared and are recorded in Other Income, Net on the accompanying unaudited condensed consolidated statements of income. All other marketable securities are accounted for as available-for-sale.

Available-for-Sale Securities: The following is a summary of NU's available-for-sale securities held in the NU supplemental benefit trust and WMECO's spent nuclear fuel trust. These securities are recorded at fair value and included in current and long-term Marketable Securities on the accompanying unaudited condensed consolidated balance sheets.

	As of September 30, 2011
			Pre-Tax		Pre-Tax
	Amortized		Unrealized		Unrealized
(Millions of Dollars)	Cost		Gains⁽¹⁾		Losses⁽¹⁾		Fair Value
NU	$	87.8	$	1.9	$	(0.3)	$	89.4
WMECO		57.3		-		(0.2)		57.1



	As of December 31, 2010
			Pre-Tax		Pre-Tax
	Amortized		Unrealized		Unrealized
(Millions of Dollars)	Cost		Gains⁽¹⁾		Losses⁽¹⁾		Fair Value
NU	$	86.3	$	1.3	$	(0.3)	$	87.3
WMECO		57.2		-		(0.1)		57.1

(1) Unrealized gains and losses on debt securities for the NU supplemental benefit trust and WMECO spent nuclear fuel trust are recorded in AOCI and Other Long-Term Assets, respectively, on the accompanying unaudited condensed consolidated balance sheets.

Unrealized Losses and Other-than-Temporary Impairment: There have been no significant unrealized losses, other-than-temporary impairments or credit losses for the NU supplemental benefit trust or WMECO spent nuclear fuel trust. 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 the NU supplemental benefit trust and in Other Long-Term Assets for the WMECO spent nuclear fuel trust. NU utilizes the specific identification basis method for the NU supplemental benefit trust securities and the average cost basis method for the WMECO spent nuclear fuel trust to compute the realized gains and losses on the sale of available-for-sale securities.

Contractual Maturities: As of September 30, 2011, the contractual maturities of available-for-sale debt securities are as follows:


	NU				WMECO
	Amortized				Amortized
(Millions of Dollars)	Cost		Fair Value		Cost		Fair Value
Less than one year	$	37.2	$	37.2	$	34.9	$	34.9
One to five years		16.1		16.2		10.7		10.6
Six to ten years		10.7		11.1		6.7		6.7
Greater than ten years		23.8		24.9		5.0		4.9
Total Debt Securities	$	87.8	$	89.4	$	57.3	$	57.1

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:

			NU				WMECO
			As of		As of		As of		As of
(Millions of Dollars)			September 30, 2011		December 31, 2010		September 30, 2011		December 31, 2010
Level 1:
	Mutual Funds		$	37.3	$	42.2	$	-	$	-
	Money Market Funds			1.3		1.8		0.4		0.3
Total Level 1			$	38.6	$	44.0	$	0.4	$	0.3
Level 2:
	U.S. Government Issued Debt Securities
		(Agency and Treasury)		2.9		17.8		-		6.0
	Corporate Debt Securities			17.1		22.5		8.5		15.6
	Asset Backed Debt Securities			27.4		11.6		8.5		4.7
	Municipal Bonds			16.4		16.1		15.7		15.4
	Other Fixed Income Securities			24.3		17.5		24.0		15.1
Total Level 2			$	88.1	$	85.5	$	56.7	$	56.8
Total Marketable Securities			$	126.7	$	129.5	$	57.1	$	57.1

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. Municipal bonds are valued using a market approach that incorporates reported trades and benchmark yields. 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. Other fixed income securities are valued using pricing models, quoted prices of securities with similar characteristics, and discounted cash flows.