Fair Value Hierarchy

Fair value is defined as the price to sell an asset or transfer a liability (i.e. the “exit price”) in an orderly transaction between market participants. U.S. GAAP prescribes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. The level in the hierarchy within which a given fair value measurement falls is determined based on the lowest level input that is significant to the measurement. The hierarchy is broken down into three levels as follows:


•	Level 1 - Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access.


•	Level 2 - Valuations based on quoted prices in active markets for similar assets or liabilities, quoted prices for identical assets or liabilities in inactive markets, or for which significant inputs are observable (e.g. interest rates, yield curves, prepayment speeds, default rates, loss severities, etc.) or can be corroborated by observable market data.


•	Level 3 - Valuations based on inputs that are unobservable and significant to the overall fair value measurement. The unobservable inputs reflect our own judgments about assumptions that market participants might use.

The availability of observable inputs can vary from financial instrument to financial instrument and is affected by a wide variety of factors including, for example, the type of financial instrument, whether the financial instrument is new and not yet established in the marketplace, and other characteristics particular to the transaction. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires significantly more judgment.

Accordingly, the degree of judgment exercised by management in determining fair value is greatest for instruments categorized in Level 3. In periods of market dislocation, the observability of prices and inputs may be reduced for many instruments. This may lead us to change the selection of our valuation technique (from market to cash flow approach) or may cause us to use multiple valuation techniques to estimate the fair value of a financial instrument. This circumstance could cause an instrument to be reclassified between levels within the fair value hierarchy.

Valuation Techniques

The valuation techniques, including significant inputs and assumptions generally used to determine the fair values of our financial instruments as well as the classification of the fair values of our financial instruments in the fair value hierarchy are described in detail below.

Fixed Maturities

At each valuation date, we use the market approach valuation technique to estimate the fair value of our fixed maturities portfolio, when possible. This market approach includes, but is not limited to, prices obtained from third party pricing services for identical or comparable securities and the use of “pricing matrix models” using observable market inputs such as yield curves, credit risks and spreads, measures of volatility, and prepayment speeds. Pricing from third party pricing services is sourced from multiple vendors, when available, and we maintain a vendor hierarchy by asset type based on historical pricing experience and vendor expertise. When prices are unavailable from pricing services, we obtain non-binding quotes from broker-dealers who are active in the corresponding markets. The valuation techniques including significant inputs generally used to determine the fair values of our fixed maturities by asset class as well as the classifications of the fair values of these securities in the fair value hierarchy are described in detail below.

U.S. government and agency

U.S. government and agency securities consist primarily of bonds issued by the U.S. Treasury and mortgage pass-through agencies such as the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation and the Government National Mortgage Association. As the fair values of U.S. Treasury securities are based on unadjusted market prices in active markets, these securities are classified as Level 1. The fair values of U.S. government agency securities are determined using the spread above the risk-free yield curve. As the yields for the risk-free yield curve and the spreads are observable market inputs, the fair values of U.S. government agency securities are classified as Level 2.

Non-U.S. government

Non-U.S. government securities include bonds issued by non-U.S. governments and their agencies along with supranational organizations (collectively also known as sovereign debt securities). The fair values of these securities are based on prices obtained from international indices or valuation models that include inputs such as interest rate yield curves, cross-currency basis index spreads, and country credit spreads for structures similar to the sovereign bond in terms of issuer, maturity and seniority. As the significant inputs used to price these securities are observable market inputs, the fair values of non-U.S. government securities are classified as Level 2.

Corporate debt

Corporate debt securities consist primarily of investment-grade debt of a wide variety of corporate issuers and industries. The fair values of these securities are generally determined using the spread above the risk-free yield curve. These spreads are generally obtained from the new issue market, secondary trading and broker-dealer quotes. As the yields for the risk-free yield curve and the spreads are observable market inputs, the fair values of corporate debt securities are classified as Level 2. Where pricing is unavailable from pricing services, we obtain non-binding quotes from broker-dealers to estimate fair value. This is generally the case when there is a low volume of trading activity and current transactions are not orderly. In this event, the fair values of these securities are classified as Level 3.

Agency RMBS

Agency RMBS consist of bonds issued by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation and the Government National Mortgage Association. The fair values of these securities are priced using a mortgage pool specific model which uses daily inputs from the active to be announced market and the spread associated with each mortgage pool based on vintage. As the significant inputs used to price these securities are observable market inputs, the fair values of Agency RMBS are classified as Level 2.

CMBS

CMBS include mostly investment-grade bonds originated by non-agencies. The fair values of these securities are determined using a pricing model which uses dealer quotes and other available trade information along with security level characteristics to determine deal specific spreads. As the significant inputs used to price these securities are observable market inputs, the fair values of CMBS securities are classified as Level 2. Where pricing is unavailable from pricing services, we obtain non-binding quotes from broker-dealers to estimate fair value. This is generally the case when there is a low volume of trading activity and current transactions are not orderly. In this event, the fair values of these securities are classified as Level 3.

Non-Agency RMBS

Non-Agency RMBS include mostly investment-grade bonds originated by non-agencies. The fair values of these securities are determined using an option adjusted spread model or other relevant models, which use inputs including available trade information or broker quotes, prepayment and default projections based on historical statistics of the underlying collateral and current market data. As the significant inputs used to price these securities are observable market inputs, the fair values of Non-Agency RMBS are classified as Level 2.

ABS

ABS include mostly investment-grade bonds backed by pools of loans with a variety of underlying collateral, including automobile loan receivables, student loans, credit card receivables, and CLO debt originated by a variety of financial institutions. The fair values of these securities are determined using a model which uses prepayment speeds and spreads sourced primarily from the new issue market. As the significant inputs used to price these securities are observable market inputs, the fair values of ABS are classified as Level 2. Where pricing is unavailable from pricing services, we obtain non-binding quotes from broker-dealers to estimate fair value. This is generally the case when there is a low volume of trading activity and current transactions are not orderly. In this event, the fair values of these securities are classified as Level 3.

Municipals

Municipals comprise revenue and general obligation bonds issued by U.S. domiciled state and municipal entities. The fair values of these securities are determined using spreads obtained from the new issue market, trade prices and broker-dealers quotes. As the significant inputs used to price these securities are observable market inputs, the fair values of municipals are classified as Level 2.

Equity Securities

Equity securities include common stocks, exchange-traded funds and bond mutual funds. As the fair values of common stocks and exchange-traded funds are based on unadjusted quoted market prices in active markets, these securities are classified as Level 1.

As bond mutual funds have daily liquidity with redemption based on the Net Asset Values per share ("NAV") of the funds, the fair values of these securities are classified as Level 2.

Other Investments

Other privately held securities include convertible preferred shares, convertible notes and notes payable. These securities are initially valued at cost which approximates fair value. In subsequent measurement periods, the fair values of these securities are determined using an internally developed discounted cash flow model. As the significant inputs used to price these securities are unobservable, the fair value of these securities are classified as Level 3.

Indirect investments in CLO-Equities are classified as Level 3 as the fair values of these securities are estimated using an income approach valuation technique (discounted cash flow model) due to the lack of observable and relevant trades in secondary markets. Direct investments in CLO-Equities are also classified as Level 3 as these securities are estimated using a liquidation valuation.

Short-Term Investments

Short-term investments primarily comprise highly liquid securities with maturities greater than three months but less than one year from the date of purchase. These securities are classified as Level 2 because these securities are typically not actively traded due to their approaching maturity and, as such, their amortized cost approximates fair value.

Derivative Instruments

Derivative Instruments include foreign currency forward contracts, exchange traded interest rate swaps and commodity contracts that are customized to our economic hedging strategies and trade in the over-the-counter derivative market. The fair values of these derivatives are determined using the market approach valuation technique based on significant observable market inputs from third party pricing vendors, non-binding broker-dealer quotes and/or recent trading activity. Accordingly, the fair values of these derivatives are classified as Level 2.

Weather derivatives relate to non-exchange traded derivative-based risk management products addressing weather risks. The fair values of these derivatives are determined using observable market inputs and unobservable inputs in combination with industry or internally developed valuation and forecasting techniques. Accordingly, the fair values of these derivatives are classified as Level 3.

Other underwriting-related derivatives include insurance and reinsurance contracts that are required to be accounted for as derivatives. These derivative contracts are initially valued at cost which approximates fair value. In subsequent measurement periods, the fair values of these derivatives are determined using internally developed discounted cash flow models. As the significant inputs used to price these derivatives are unobservable, the fair value of these contracts are classified as Level 3.

Insurance-linked Securities

Insurance-linked securities comprise an investment in a catastrophe bond. As pricing is unavailable from pricing services, we obtain non-binding quotes from broker-dealers to estimate the fair values of these securities. Pricing is generally unavailable when there is a low volume of trading activity and current transactions are not orderly. Accordingly, the fair values of these securities are classified as Level 3.

Cash Settled Awards

Cash settled awards comprise restricted stock units that form part of our compensation program. Although the fair values of these awards are determined using observable quoted market prices in active markets, the restricted stock units are not actively traded. Accordingly, the fair values of these liabilities are classified as Level 2.

The tables below present the financial instruments measured at fair value on a recurring basis for the periods indicated:



	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair value based on NAV practical expedient		Total Fair Value

At September 30, 2017
Assets
Fixed maturities
U.S. government and agency	$	1,495,423	$	51,895	$	—	$	—	$	1,547,318
Non-U.S. government	—		573,640		—		—		573,640
Corporate debt	—		4,442,951		61,016		—		4,503,967
Agency RMBS	—		2,306,822		—		—		2,306,822
CMBS	—		669,736		—		—		669,736
Non-Agency RMBS	—		43,817		—		—		43,817
ABS	—		1,264,855		24,015		—		1,288,870
Municipals	—		152,216		—		—		152,216
	1,495,423		9,505,932		85,031		—		11,086,386
Equity securities
Common stocks	14,826		—		—		—		14,826
Exchange-traded funds	454,194		—		—		—		454,194
Bond mutual funds	—		190,731		—		—		190,731
	469,020		190,731		—		—		659,751
Other investments
Hedge funds	—		—		—		399,097		399,097
Direct lending funds	—		—		—		232,389		232,389
Private equity funds	—		—		—		71,896		71,896
Real estate funds	—		—		—		46,691		46,691
Other privately held investments	—		—		43,398		—		43,398
CLO-Equities	—		—		36,782		—		36,782
	—		—		80,180		750,073		830,253
Short-term investments	—		15,282		—		—		15,282
Other assets
Derivative instruments (see Note 6)	—		5,859		—		—		5,859
Insurance-linked securities	—		—		24,976		—		24,976
Total Assets	$	1,964,443	$	9,717,804	$	190,187	$	750,073	$	12,622,507
Liabilities
Derivative instruments (see Note 6)	$	—	$	1,873	$	11,844	$	—	$	13,717
Cash settled awards (see Note 9)	—		18,369		—		—		18,369
Total Liabilities	$	—	$	20,242	$	11,844	$	—	$	32,086



	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair value based on NAV practical expedient		Total Fair Value

At December 31, 2016
Assets
Fixed maturities
U.S. government and agency	$	1,583,106	$	72,963	$	—	$	—	$	1,656,069
Non-U.S. government	—		565,834		—		—		565,834
Corporate debt	—		4,524,868		75,875		—		4,600,743
Agency RMBS	—		2,465,135		—		—		2,465,135
CMBS	—		663,176		3,061		—		666,237
Non-Agency RMBS	—		56,921		—		—		56,921
ABS	—		1,204,750		17,464		—		1,222,214
Municipals	—		163,961		—		—		163,961
	1,583,106		9,717,608		96,400		—		11,397,114
Equity securities
Common stocks	78		—		—		—		78
Exchange-traded funds	514,707		—		—		—		514,707
Bond mutual funds	—		123,959		—		—		123,959
	514,785		123,959		—		—		638,744
Other investments
Hedge funds	—		—		—		498,150		498,150
Direct lending funds	—		—		—		134,650		134,650
Private equity funds	—		—		—		81,223		81,223
Real estate funds	—		—		—		13,354		13,354
Other privately held investments	—		—		42,142		—		42,142
CLO-Equities	—		—		60,700		—		60,700
	—		—		102,842		727,377		830,219
Short-term investments	—		127,461		—		—		127,461
Other assets
Derivative instruments (see Note 6)	—		14,365		2,532		—		16,897
Insurance-linked securities	—		—		25,023		—		25,023
Total Assets	$	2,097,891	$	9,983,393	$	226,797	$	727,377	$	13,035,458
Liabilities
Derivative instruments (see Note 6)	$	—	$	9,076	$	6,500	$	—	$	15,576
Cash settled awards (see Note 9)	—		48,432		—		—		48,432
Total Liabilities	$	—	$	57,508	$	6,500	$	—	$	64,008

During 2017 and 2016, there were no transfers between Levels 1 and 2.

Except certain fixed maturities and insurance-linked securities priced using broker-dealer quotes (underlying inputs are not available), the following table quantifies the significant unobservable inputs used in estimating fair values at September 30, 2017 for investments classified as Level 3 in the fair value hierarchy.



	Fair Value			Valuation Technique	Unobservable Input	Range	Weighted Average

Other investments - CLO-Equities	$	32,141		Discounted cash flow	Default rates	3.8%	3.8%
					Loss severity rate	35.0%	35.0%
					Collateral spreads	3.0%	3.0%
					Estimated maturity dates	7 years	7 years

	4,641			Liquidation value	Fair value of collateral	100%	100%
					Discount margin	0% - 17.8%	2.7%

Other investments - Other privately held investments	43,398			Discounted cash flow	Discount rate	6.0% - 8.0%	7.5%

Derivatives - Other underwriting-related derivatives	$	(11,844	)	Discounted cash flow	Discount rate	2.3%	2.3%

The CLO-Equities market continues to be relatively inactive with only a small number of transactions being observed, particularly as it relates to transactions involving our CLO-Equities. Accordingly, fair values of investments in CLO-Equities are determined using models. Given that all of our direct investments in CLO-Equities are past their reinvestment period, there is uncertainty over the remaining time to maturity. As such our direct investments in CLO-Equities are estimated using a liquidation valuation. Indirect investments in CLO-Equities are valued using a discounted cash flow model prepared by an external manager.

The liquidation valuation is based on the fair values of the net underlying collateral which is determined by applying market discount margins by credit quality bucket. An increase (decrease) in the market discount margin would result in a decrease (increase) in value of our CLO-Equities.

Regarding the discounted cash flow model, the default and loss severity rates are the most judgmental unobservable market inputs to which the valuation of CLO-Equities is most sensitive. A significant increase (decrease) in either of these significant inputs in isolation would result in lower (higher) fair value estimates for investments in CLO-Equities and, in general, a change in default rate assumptions will be accompanied by a directionally similar change in loss severity rate assumptions. Collateral spreads and estimated maturity dates are less judgmental inputs as they are based on the historical average of actual spreads and the weighted average life of the current underlying portfolios, respectively. A significant increase (decrease) in either of these significant inputs in isolation would result in higher (lower) fair value estimates for investments in CLO-Equities. In general, these inputs have no significant interrelationship with each other or with default and loss severity rates.

On a quarterly basis, our valuation process for CLO-Equities includes a review of the underlying collateral along with related discount margins by credit quality bucket used in the liquidation valuation and a review of the underlying cash flows and key assumptions used in the discounted cash flow model. The above significant unobservable inputs are reviewed and updated based on information obtained from secondary markets, including information received from the managers of our CLO-Equities portfolio. In order to assess the reasonableness of the inputs we use in our models, we maintain an understanding of current market conditions, historical results, as well as emerging trends that may impact future cash flows. In addition,we update the assumptions we use in our models through regular communication with industry participants and ongoing monitoring of the deals in which we participate (e.g. default and loss severity rate trends).

Other privately held securities are initially valued at cost which approximates fair value. In subsequent measurement periods, the fair values of these securities are determined using internally developed discounted cash flow models. These models include inputs that are specific to each investment. The inputs used in the fair value measurements include dividend or interest rates and appropriate discount rates. The selection of an appropriate discount rate is judgmental and is the most significant unobservable input used in the valuation of these securities. A significant increase (decrease) in this input in isolation could result in a significantly lower (higher) fair value measurement for other privately held securities. Where relevant, we also consider the contractual agreements which stipulate methodologies for calculating the dividend rate to be paid upon liquidation, conversion or redemption. In order to assess the reasonableness of the inputs we use in the discounted cash flow models, we maintain an understanding of current market conditions, historical results, as well as investee specific information that may impact future cash flows.

Other underwriting-related derivatives are initially valued at cost which approximates fair value. In subsequent measurement periods, the fair values of these derivatives are determined using internally developed discounted cash flow models which uses appropriate discount rates. The selection of an appropriate discount rate is judgmental and is the most significant unobservable input used in the valuation of these derivatives. A significant increase (decrease) in this input in isolation could result in a significantly lower (higher) fair value measurement for the derivative contracts. In order to assess the reasonableness of the inputs we use in the discounted cash flow model, we maintain an understanding of current market conditions, historical results, as well as contract specific information that may impact future cash flows.

The following tables present changes in Level 3 for financial instruments measured at fair value on a recurring basis for the periods indicated:



	Opening Balance		Transfers into Level 3		Transfers out of Level 3			Included in earnings⁽¹⁾			Included in OCI⁽²⁾			Purchases		Sales			Settlements/ Distributions			Closing Balance		Change in unrealized investment gain/(loss)⁽³⁾

Three months ended September 30, 2017
Fixed maturities
Corporate debt	$	68,320	$	—	$	(1,208	)	$	(835	)	$	(9	)	$	—	$	(2,274	)	$	(2,978	)	$	61,016	$	—
CMBS	—		—		—			—			—			—		—			—			—		—
ABS	5,999		—		(6,001		)	—			10			24,007		—			—			24,015		—
	74,319		—		(7,209		)	(835		)	1			24,007		(2,274		)	(2,978		)	85,031		—
Other investments
Other privately held investments	42,938		—		—			460			—			—		—			—			43,398		460
CLO - Equities	47,076		—		—			1,402			—			—		—			(11,696		)	36,782		1,402
	90,014		—		—			1,862			—			—		—			(11,696		)	80,180		1,862
Other assets
Derivative instruments	—		—		—			—			—			—		—			—			—		—
Insurance-linked securities	25,047		—		—			(71		)	—			—		—			—			24,976		(71		)
	25,047		—		—			(71		)	—			—		—			—			24,976		(71		)
Total assets	$	189,380	$	—	$	(7,209	)	$	956		$	1		$	24,007	$	(2,274	)	$	(14,674	)	$	190,187	$	1,791

Other liabilities
Derivative instruments	$	12,209	$	—	$	—		$	(291	)	$	—		$	—	$	—		$	(74	)	$	11,844	$	(291	)
Total liabilities	$	12,209	$	—	$	—		$	(291	)	$	—		$	—	$	—		$	(74	)	$	11,844	$	(291	)

Nine months ended September 30, 2017
Fixed maturities
Corporate debt	$	75,875	$	1,536	$	(3,112	)	$	(762	)	$	(392	)	$	19,181	$	(21,475	)	$	(9,835	)	$	61,016	$	—
CMBS	3,061		—		(9,418		)	—			17			9,400		—			(3,060		)	—		—
ABS	17,464		—		(24,949		)	—			1,493			30,007		—			—			24,015		—
	96,400		1,536		(37,479		)	(762		)	1,118			58,588		(21,475		)	(12,895		)	85,031		—
Other investments
Other privately held investments	42,142		—		—			1,256			—			—		—			—			43,398		1,256
CLO - Equities	60,700		—		—			3,930			—			—		—			(27,848		)	36,782		3,930
	102,842		—		—			5,186			—			—		—			(27,848		)	80,180		5,186
Other assets
Derivative instruments	2,532		—		—			653			—			—		—			(3,185		)	—		—
Insurance-linked securities	25,023		—		—			(47		)	—			—		—			—			24,976		(47		)
	27,555		—		—			606			—			—		—			(3,185		)	24,976		(47		)
Total assets	$	226,797	$	1,536	$	(37,479	)	$	5,030		$	1,118		$	58,588	$	(21,475	)	$	(43,928	)	$	190,187	$	5,139

Other liabilities
Derivative instruments	$	6,500	$	—	$	—		$	9,991		$	—		$	12,135	$	—		$	(16,782	)	$	11,844	$	(291	)
Total liabilities	$	6,500	$	—	$	—		$	9,991		$	—		$	12,135	$	—		$	(16,782	)	$	11,844	$	(291	)



	Opening Balance		Transfers into Level 3		Transfers out of Level 3			Included in earnings⁽¹⁾			Included in OCI⁽²⁾			Purchases		Sales			Settlements/ Distributions			Closing Balance		Change in unrealized investment gain/(loss)⁽³⁾

Three months ended September 30, 2016
Fixed maturities
Corporate debt	$	62,022	$	—	$	—		$	(9	)	$	100		$	7,563	$	—		$	(584	)	$	69,092	$	—
CMBS	10,210		—		—			—			(48		)	—		—			(1,242		)	8,920		—
ABS	—		—		—			—			—			—		—			—			—		—
	72,232		—		—			(9		)	52			7,563		—			(1,826		)	78,012		—
Other investments
Other privately held investments	41,755		—		—			(355		)	—			1,500		—			—			42,900		(355		)
CLO - Equities	65,883		—		—			8,419			—			—		—			(10,519		)	63,783		8,419
	107,638		—		—			8,064			—			1,500		—			(10,519		)	106,683		8,064
Other assets
Derivative instruments	5		—		—			665			—			1,818		—			—			2,488		665
Insurance-linked securities	25,025		—		—			258			—			—		—			—			25,283		258
	25,030		—		—			923			—			1,818		—			—			27,771		923
Total assets	$	204,900	$	—	$	—		$	8,978		$	52		$	10,881	$	—		$	(12,345	)	$	212,466	$	8,987

Other liabilities
Derivative instruments	$	1,978	$	—	$	—		$	(169	)	$	—		$	6,384	$	—		$	(9	)	$	8,184	$	335
Total liabilities	$	1,978	$	—	$	—		$	(169	)	$	—		$	6,384	$	—		$	(9	)	$	8,184	$	335

Nine months ended September 30, 2016
Fixed maturities
Corporate debt	$	38,518	$	20,412	$	(1,955	)	$	(988	)	$	1,188		$	17,107	$	(4,015	)	$	(1,175	)	$	69,092	$	—
CMBS	10,922		—		—			—			(134		)	—		—			(1,868		)	8,920		—
ABS	—		—		—			—			—			—		—			—			—		—
	49,440		20,412		(1,955		)	(988		)	1,054			17,107		(4,015		)	(3,043		)	78,012		—
Other investments
Other privately held investments	—		—		—			(1,505		)	—			44,405		—			—			42,900		(1,505		)
CLO - Equities	27,257		36,378		—			17,431			—			—		—			(17,283		)	63,783		17,431
	27,257		36,378		—			15,926			—			44,405		—			(17,283		)	106,683		15,926
Other assets
Derivative instruments	4,395		—		—			3,255			—			3,623		—			(8,785		)	2,488		669
Insurance-linked securities	24,925		—		—			358			—			—		—			—			25,283		358
	29,320		—		—			3,613			—			3,623		—			(8,785		)	27,771		1,027
Total assets	$	106,017	$	56,790	$	(1,955	)	$	18,551		$	1,054		$	65,135	$	(4,015	)	$	(29,111	)	$	212,466	$	16,953

Other liabilities
Derivative instruments	$	10,937	$	—	$	—		$	2,445		$	—		$	7,189	$	—		$	(12,387	)	$	8,184	$	457
Total liabilities	$	10,937	$	—	$	—		$	2,445		$	—		$	7,189	$	—		$	(12,387	)	$	8,184	$	457


(1)	Gains and losses included in earnings on fixed maturities are included in net realized investment gains (losses). Gains and (losses) included in earnings on other investments are included in net investment income. Gains (losses) on weather derivatives included in earnings are included in other insurance-related income.


(2)	Gains and losses included in other comprehensive income (“OCI”) on fixed maturities are included in unrealized gains (losses) arising during the period.


(3)	Change in unrealized investment gain (loss) relating to assets held at the reporting date.

The transfers into and out of fair value hierarchy levels reflect the fair value of the securities at the end of the reporting period.

Transfers into Level 3 from Level 2

There were no transfers to Level 3 from Level 2 made during the three months ended September 30, 2017. The transfers to Level 3 from Level 2 made during the nine months ended September 30, 2017 were primarily due to the lack of observable market inputs and multiple quotes from pricing vendors and broker-dealers for certain fixed maturities.

There were no transfers to Level 3 from Level 2 made during the three months ended September 30, 2016. The transfers into Level 3 made during the nine months ended September 30, 2016 were primarily due to the lack of observable market inputs and multiple quotes from pricing vendors and broker-dealers for certain fixed maturities and as a result of a change in the valuation methodology used to fair value the CLO-equity fund. An income approach valuation technique (discounted cash flow model) was used to estimate the fair value of the CLO-equity fund at September 30, 2016. As the NAV practical expedient was not used to determine the fair value of the CLO-equity fund, the fair value of the fund was categorized within the fair value hierarchy.

Transfers out of Level 3 into Level 2

The transfers into Level 2 from Level 3 made during the three and nine months ended September 30, 2017 were primarily due to the availability of observable market inputs and quotes from pricing vendors on certain fixed maturities.

There were no transfers to Level 2 from Level 3 made during the three months ended September 30, 2016. The transfers to Level 2 from Level 3 made during the nine months ended September 30, 2016 were primarily due to the availability of observable market inputs and quotes from pricing vendors on certain fixed maturities.

Measuring the Fair Value of Other Investments Using Net Asset Valuations

The fair values of hedge funds, direct lending funds, private equity funds and real estate funds are estimated using NAVs as advised by external fund managers or third party administrators. For these funds, NAVs are based on the manager's or administrator's valuation of the underlying holdings in accordance with the fund's governing documents and in accordance with U.S. GAAP.

If there is a reporting lag between the current period end and reporting date of the latest available fund valuation for any hedge fund, we estimate fair values by starting with the most recently available fund valuation and adjusting for return estimates as well as any subscriptions, redemptions and distributions that took place during the current period. Return estimates are obtained from the relevant fund managers. Accordingly, we do not typically have a reporting lag in fair value measurements of these funds. Historically, our valuation estimates incorporating these return estimates have not significantly diverged from the subsequently received NAVs.

For direct lending funds, private equity funds, real estate funds and two of our hedge funds, valuation statements are typically released on a three month reporting lag therefore we estimate fair value of these funds by starting with the prior quarter-end fund valuations and adjusting for capital calls, redemptions, drawdowns and distributions. Return estimates are not available from the relevant fund managers for these funds. Accordingly, we typically have a reporting lag in our fair value measurements of these funds. In 2017, funds reported on a lag represented 51% (2016: 35%) of our total other investments balance.

We often do not have access to financial information relating to the underlying securities held within the funds, therefore management is unable to corroborate the fair values placed on the securities underlying the asset valuations provided by fund managers or fund administrators. In order to assess the reasonableness of the NAVs, we perform a number of monitoring procedures on a quarterly basis, to assess the quality of the information provided by fund managers and funds administrators. These procedures include, but are not limited to, regular review and discussion of each fund's performance with its manager, regular evaluation of fund performance against applicable benchmarks and the backtesting of our fair value estimates against subsequently received NAVs. Backtesting involves comparing our previously reported fair values for each fund against NAVs per audited financial statements (for year-end values) and final NAVs from fund managers and fund administrators (for interim values).

The fair values of hedge funds, direct lending funds, private equity funds and real estate funds are measured using the NAV practical expedient, therefore the fair values of these funds have not been categorized within the fair value hierarchy.

Financial Instruments Disclosed, But Not Carried, at Fair Value

The fair value of financial instruments accounting guidance also applies to financial instruments disclosed, but not carried, at fair value, except for certain financial instruments, including insurance contracts.

The carrying values of cash and cash equivalents (including restricted amounts), accrued investment income, receivable for investments sold, certain other assets, payable for investments purchased and certain other liabilities approximated their fair values at September 30, 2017, due to their respective short maturities. As these financial instruments are not actively traded, their fair values are classified as Level 2.

The carrying value of mortgage loans held-for-investment approximated their fair value at September 30, 2017. The fair values of mortgage loans are primarily determined by estimating expected future cash flows and discounting them using current interest rates for similar mortgage loans with similar credit risk, or are determined from pricing for similar loans. As mortgage loans are not actively traded their fair values are classified as Level 3.

At September 30, 2017, senior notes are recorded at amortized cost with a carrying value of $994 million (2016: $993 million) and a fair value of $1.1 billion (2016: $1.0 billion). The fair values of these notes are based on prices obtained from a third party pricing service and are determined using the spread above the risk-free yield curve. These spreads are generally obtained from the new issue market, secondary trading and broker-dealer quotes. As these spreads and the yields for the risk-free yield curve are observable market inputs, the fair values of senior notes are classified as Level 2.