The following realized gains and (losses) on investments exclude amounts required to adjust future policy benefits for the run-off settlement annuity business:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(In millions)	2016		2015		2016		2015
Fixed maturities	$	7	$	(57)	$	(5)	$	(38)
Equity securities		(1)		28		-		42
Commercial mortgage loans		-		-		4		2
Other investments, including derivatives		69		39		111		98
Realized investment gains before income taxes		75		10		110		104
Less income taxes		27		3		39		36
Net realized investment gains	$	48	$	7	$	71	$	68

Included in these realized investment gains (losses) were pre-tax asset write-downs as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(In millions)	2016		2015		2016		2015
Other-than-temporary impairments on debt securities:
Credit-related	$	-	$	(3)	$	(19)	$	(4)
Non credit-related ⁽¹⁾		(1)		(55)		(12)		(69)
Total other-than-temporary impairments on debt securities		(1)		(58)		(31)		(73)
Other asset write-downs⁽²⁾		-		(1)		(13)		(12)
Total	$	(1)	$	(59)	$	(44)	$	(85)

(1) These write-downs pertain to other-than-temporary declines in fair values due to increases in market yields (widening of credit spreads), particularly within the energy sector, for certain below investment grade fixed maturities with an increased probability of sales activity prior to recovery of their amortized cost basis.
(2) Other asset write-downs include other-than-temporary declines in fair values of equity securities, increases in valuation reserves on commercial mortgage loans and asset write-downs related to real estate investments and security partnerships.

Sales information for available-for-sale fixed maturities and equity securities was as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
(In millions)	2016		2015		2016		2015
Proceeds from sales	$	300	$	275	$	1,012	$	1,452
Gross gains on sales	$	9	$	31	$	43	$	82
Gross losses on sales	$	-	$	3	$	6	$	7

The amortized cost and fair value by contractual maturity periods for fixed maturities were as follows at September 30, 2016:

		Amortized		Fair
(In millions)		Cost		Value
Due in one year or less	$	1,550	$	1,557
Due after one year through five years		6,581		6,928
Due after five years through ten years		7,353		7,881
Due after ten years		3,447		4,379
Mortgage and other asset-backed securities		461		499
Total	$	19,392	$	21,244

Actual maturities of these securities could differ from their contractual maturities used in the table above. This could occur because issuers may have the right to call or prepay obligations, with or without penalties.

Gross unrealized appreciation (depreciation) on fixed maturities by type of issuer is shown below.

				Gross		Gross
				Unrealized		Unrealized
		Amortized		Appre-		Depre-		Fair
		Cost		ciation		ciation		Value
(In millions)	September 30, 2016
Federal government and agency	$	452	$	298	$	-	$	750
State and local government		1,360		148		-		1,508
Foreign government		2,104		221		(3)		2,322
Corporate		15,015		1,192		(42)		16,165
Mortgage-backed		35		2		(1)		36
Other asset-backed		426		40		(3)		463
Total	$	19,392	$	1,901	$	(49)	$	21,244

(In millions)	December 31, 2015
Federal government and agency	$	528	$	251	$	-	$	779
State and local government		1,496		147		(2)		1,641
Foreign government		1,870		147		(3)		2,014
Corporate		14,022		632		(206)		14,448
Mortgage-backed		48		2		(1)		49
Other asset-backed		492		39		(7)		524
Total	$	18,456	$	1,218	$	(219)	$	19,455

The above table includes investments with a fair value of $2.9 billion at September 30, 2016 and $2.7 billion at December 31, 2015 supporting liabilities of the Company's run-off settlement annuity business. These investments had gross unrealized appreciation of $752 million and gross unrealized depreciation of $2 million at September 30, 2016, compared with gross unrealized appreciation of $521 million and gross unrealized depreciation of $38 million at December 31, 2015. Such unrealized amounts are reported in future policy benefit liabilities rather than accumulated other comprehensive income.

Review of declines in fair value. Management reviews fixed maturities with a decline in fair value from cost for impairment based on criteria that include:

The table below summarizes fixed maturities in an unrealized loss position at September 30, 2016 by the length of time these securities have been in an unrealized loss position. These fixed maturities were primarily corporate securities with a decline in fair value that reflects an increase in market yields since purchase.

	September 30, 2016
	Fair		Amortized		Unrealized		Number
(Dollars in millions)	Value		Cost		Depreciation		of Issues
One year or less:
Investment grade	$	784	$	797	$	(13)	329
Below investment grade	$	277	$	283	$	(6)	122
More than one year:
Investment grade	$	331	$	345	$	(14)	58
Below investment grade	$	181	$	197	$	(16)	32

There were no available for sale equity securities with a significant unrealized loss reflected in accumulated other comprehensive income at September 30, 2016. Equity securities also include hybrid investments consisting of preferred stock with call features that are carried at fair value with changes in fair value reported in other realized investment gains (losses) and dividends reported in net investment income. As of September 30, 2016, fair values of these securities were $36 million and amortized cost was $51 million. As of December 31, 2015, fair values of these securities were $52 million and amortized cost was $66 million.

Mortgage loans held by the Company are made exclusively to commercial borrowers and are diversified by property type, location and borrower. Loans are generally issued at a fixed rate of interest and are secured by high quality, primarily completed and substantially leased operating properties.

Credit quality. The Company regularly evaluates and monitors credit risk, beginning with the initial underwriting of a mortgage loan and continuing throughout the investment holding period. Mortgage origination professionals employ an internal credit quality rating system designed to evaluate the relative risk of the transaction at origination that is then updated each year as part of the annual portfolio loan review. The Company evaluates and monitors credit quality on an ongoing basis, classifying each loan as a loan in good standing, potential problem loan or problem loan.

Quality ratings are based on our evaluation of a number of key inputs related to the loan including real estate market-related factors such as rental rates and vacancies, and property-specific inputs such as growth rate assumptions and lease rollover statistics. However, the two most significant contributors to the credit quality rating are the debt service coverage and loan-to-value ratios. The debt service coverage ratio measures the amount of property cash flow available to meet annual interest and principal payments on the debt, with a ratio below 1.0 indicating that there is not enough cash flow to cover the required loan payments. The loan-to-value ratio, commonly expressed as a percentage, compares the amount of the loan to the fair value of the underlying property collateralizing the loan.

The following tables summarize the credit risk profile of the Company's commercial mortgage loan portfolio based on loan-to-value and debt service coverage ratios, as of September 30, 2016 and December 31, 2015:

		Debt Service Coverage Ratio
		1.30x or		1.20x to		1.10x to		1.00x to		Less than
Loan-to-Value Ratios		Greater		1.29x		1.19x		1.09x		1.00x		Total
(In millions)				September 30, 2016
Below 50%	$	465	$	15	$	-	$	-	$	-	$	480
50% to 59%		518		24		19		30		-		591
60% to 69%		651		14		-		-		-		665
70% to 79%		-		-		30		-		35		65
80% to 89%		-		-		-		-		-		-
90% to 100%		-		-		-		-		21		21
Total	$	1,634	$	53	$	49	$	30	$	56	$	1,822



		Debt Service Coverage Ratio
		1.30x or		1.20x to		1.10x to		1.00x to		Less than
Loan-to-Value Ratios		Greater		1.29x		1.19x		1.09x		1.00x		Total
(In millions)					December 31, 2015
Below 50%	$	261	$	2	$	-	$	67	$	-	$	330
50% to 59%		683		-		-		24		-		707
60% to 69%		590		14		-		19		-		623
70% to 79%		-		-		-		30		36		66
80% to 89%		40		-		-		-		-		40
90% to 100%		-		-		-		-		98		98
Total	$	1,574	$	16	$	-	$	140	$	134	$	1,864

The Company's annual in-depth review of its commercial mortgage loan investments is the primary mechanism for identifying emerging risks in the portfolio. The most recent review was completed by the Company's investment professionals in the second quarter of 2016 and included an analysis of each underlying property's most recent annual financial statements, rent rolls, operating plans, budgets, a physical inspection of the property and other pertinent factors. Based on historical results, current leases, lease expirations and rental conditions in each market, the Company estimates the current year and future stabilized property income and fair value and categorizes the investments as loans in good standing, potential problem loans or problem loans. The results of the 2016 review showed improvement from the prior review in each of the key metrics and confirmed the overall strength of the portfolio. Based on property values and cash flows estimated as part of this review, and considering updates for loans where material changes were subsequently identified, the portfolio's average loan-to-value ratio improved to 56% at September 30, 2016 compared with 58% at December 31, 2015 and the portfolio's average debt service coverage ratio improved to 1.93 at September 30, 2016 compared with 1.78 at December 31, 2015. These improvements are primarily attributable to improvements in property operations and the relative stability of these metrics is primarily due to low portfolio turnover.

The Company will reevaluate a loan's credit quality between annual reviews if new property information is received or an event such as delinquency or a borrower's request for restructure causes management to believe that the Company's estimate of financial performance, fair value or the risk profile of the underlying property has been impacted.

Potential problem mortgage loans are considered current (no payment is more than 59 days past due), but they exhibit certain characteristics that increase the likelihood of future default. The characteristics management considers include, but are not limited to, the deterioration of debt service coverage below 1.0, estimated loan-to-value ratios increasing to 100% or more, downgrade in quality rating and requests from the borrower for restructuring. In addition, loans are considered potential problems if principal or interest payments are past due by more than 30 but less than 60 days. Problem mortgage loans are either in default by 60 days or more or have been restructured as to terms that could include concessions on interest rate, principal payment or maturity date. The Company monitors each problem and potential problem mortgage loan on an ongoing basis, and updates the loan categorization and quality rating when warranted.

Problem and potential problem mortgage loans, net of valuation reserves, totaled $21 million at September 30, 2016 and $139 million at December 31, 2015.

Impaired commercial mortgage loans. A commercial mortgage loan is considered impaired when it is probable that the Company will not collect all amounts due according to the terms of the original loan agreement. These loans are included in either problem or potential problem loans. The Company monitors credit risk and assesses the impairment of loans individually and on a consistent basis for all loans in the portfolio. Impaired loans are carried at the lower of unpaid principal balance or the fair value of the underlying real estate. Certain commercial mortgage loans without valuation reserves are considered impaired because the Company will not collect all interest due according to the terms of the original agreements; however, the Company expects to recover the unpaid principal because it is less than the fair value of the underlying real estate.

The carrying value of the Company's impaired commercial mortgage loans and related valuation reserves were as follows:

(In millions)		September 30, 2016					December 31, 2015
		Gross		Reserves		Net		Gross		Reserves		Net
Impaired commercial mortgage loans with valuation reserves	$	26	$	(5)	$	21	$	113	$	(15)	$	98
Impaired commercial mortgage loans without valuation reserves		-		-		-		-		-		-
Total	$	26	$	(5)	$	21	$	113	$	(15)	$	98

The average recorded investment in impaired loans decreased to $83 million during the nine months ended September 30, 2016 versus $129 million during the nine months ended September 30, 2015, partially due to foreclosing on one impaired loan. Because of the risk profile of the underlying investment, the Company recognizes interest income on impaired mortgage loans only when payment is actually received.

Changes in valuation reserves for commercial mortgage loans were not material for the nine months ended September 30, 2016 and 2015.

Short-term investments and cash equivalents included corporate securities of $2.3 billion, federal government securities of $567 million and money market funds of $40 million as of September 30, 2016. The Company's short-term investments and cash equivalents as of December 31, 2015 included corporate securities of $925 million, federal government securities of $220 million and money market funds of $55 million.