3. Investment Securities

Investment securities at December 31, 2015 and 2014 are as follows:

2015
Available for sale securities:
Sponsored funds	$	40,552
Sponsored privately offered funds		825

Total available for sale securities		41,377
Trading securities:
Mortgage-backed securities		20
Corporate bond		5
Common stock		87
Sponsored funds		29,701

Total trading securities		29,813
Equity method securities:
Sponsored funds		217,380
Sponsored privately offered funds		3,173

Total equity method securities		220,553

Total securities	$	291,743

The following is a summary of the gross unrealized gains (losses) related to securities classified as available for sale at December 31, 2015:

Available for sale securities:	Amortized cost		Unrealized gains		Unrealized losses		Fair value
	(in thousands)
Sponsored funds	$	46,800		434		(6,682)		40,552
Sponsored privately offered funds		500		325		—		825

	$	47,300		759		(6,682)		41,377

2014
Available for sale securities:
Sponsored funds	$	157,460
Sponsored privately offered funds		3,810

Total available for sale securities		161,270

Trading securities:
Mortgage-backed securities		28
Common stock		72
Sponsored funds		81,913

Total trading securities		82,013

Total securities	$	243,283

The following is a summary of the gross unrealized gains (losses) related to securities classified as available for sale at December 31, 2014:

Available for sale securities:	Amortized cost		Unrealized gains		Unrealized losses		Fair value
Sponsored funds	$	160,675		2,177		(5,392)		157,460
Sponsored privately offered funds		1,750		2,060		—		3,810

	$	162,425		4,237		(5,392)		161,270

Sponsored funds

3,476

(166)

33,619

(6,516)

37,095

(6,682)

Based upon our assessment of these sponsored funds, the time frame the sponsored funds have been in a loss position and our intent to hold the sponsored funds until they have recovered, we determined that a write-down of fair value was not necessary at December 31, 2015.

The corporate bond accounted for as trading matures in 2018. Mortgage-backed securities accounted for as trading and held as of December 31, 2015 mature in 2022.

Investment securities with fair values of $102.2 million, $301.0 million and $442.0 million were sold during 2015, 2014 and 2013, respectively. During 2015, net realized gains of $3.0 million and $0.6 million were recognized from the sale of $31.6 million in available for sale securities and the sale of $65.9 million in trading securities, respectively, and net realized losses of $0.5 million were recognized from the sale of $5.3 million in equity method securities. During 2014, net realized gains of $5.1 million and $4.1 million were recognized from the sale of $149.8 million in available for sale securities and the sale of $151.2 million in trading securities, respectively. During 2013, net realized gains of $14.4 million and $7.7 million were recognized from the sale of $247.0 million in available for sale securities and the sale of $195.0 million in trading securities, respectively.

Accounting standards establish a framework for measuring fair value and a three-level hierarchy for fair value measurements based upon the transparency of inputs to the valuation of the asset. Inputs may be observable or unobservable and refer broadly to the assumptions that market participants would use in pricing the asset. An individual investment's fair value measurement is assigned a level based upon the observability of the inputs that are significant to the overall valuation. The three-level hierarchy of inputs is summarized as follows:

Level 1—Investments are valued using quoted prices in active markets for identical securities.

Level 2—Investments are valued using other significant observable inputs, including quoted prices in active markets for similar securities.

Level 3—Investments are valued using significant unobservable inputs, including the Company's own assumptions in determining the fair value of investments.

Assets classified as Level 2 can have a variety of observable inputs. These observable inputs are collected and utilized, primarily by an independent pricing service, in different evaluated pricing approaches depending upon the specific asset to determine a value. The fair value of municipal bonds is measured based on pricing models that take into account, among other factors, information received from market makers and broker/dealers, current trades, bid-wants lists, offerings, market movements, the callability of the bond, state of issuance and benchmark yield curves. The fair value of corporate bonds is measured using various techniques, which consider recently executed transactions in securities of the issuer or comparable issuers, market price quotations (where observable), bond spreads and fundamental data relating to the issuer. The fair value of equity derivatives is measured based on active market broker quotes, evaluated broker quotes and evaluated prices from vendors.

Securities' values classified as Level 3 are primarily determined through the use of a single quote (or multiple quotes) from dealers in the securities using proprietary valuation models. These quotes involve significant unobservable inputs, and thus, the related securities are classified as Level 3 securities.

The following tables summarize our investment securities as of December 31, 2015 and 2014 that are recognized in our consolidated balance sheets using fair value measurements based on the differing levels of inputs. There were no transfers between levels for the years ended December 31, 2015 or 2014.

2015	Level 1		Level 2		Level 3		Total

	(in thousands)
Available for sale securities:
Sponsored funds	$	40,552		—		—		40,552
Sponsored privately offered funds measured at net asset value (2)		—		—		—		825
Trading securities:
Mortgage-backed securities		—		20		—		20
Corporate bonds		—		5		—		5
Common stock		87		—		—		87
Sponsored funds		29,701		—		—		29,701
Equity method securities: (1)
Sponsored funds		217,380		—		—		217,380
Sponsored privately offered funds measured at net asset value (2)		—		—		—		3,173

Total	$	287,720		25		—		291,743

2014	Level 1		Level 2		Level 3		Total

	(in thousands)
Available for sale securities:
Sponsored funds	$	157,460		—		—		157,460
Sponsored privately offered funds measured at net asset value (2)		—		—		—		3,810
Trading securities:
Mortgage-backed securities		—		28		—		28
Common stock		72		—		—		72
Sponsored funds		81,913		—		—		81,913

Total	$	239,445		28		—		243,283


(1)	Substantially all of the Company's equity method investments are investment companies that record their underlying investments at fair value. Fair value is measured using the Company's share of the investee's underlying net income or loss, which is predominantly representative of fair value adjustments in the investments held by the investee.
(2)	Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been categorized in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets.