We invest surplus funds in excess of operational requirements in a diversified portfolio of marketable securities, with the objectives of delivering competitive returns, maintaining a high degree of liquidity, and seeking to avoid the permanent impairment of principal. A summary of our investments in marketable equity and debt securities as of June 30, 2024, are as follows:

Investments - current were as follows (in thousands):

		June 30, 2024		December 31, 2023
Marketable equity securities	$	57,171	$	62,978
U.S. treasury securities		40,443		41,313
Short-term investments	$	97,614	$	104,291

Investments- noncurrent were as follows (in thousands):

		June 30, 2024		December 31, 2023
U.S. treasury securities	$	25,333	$	13,653
Marketable debt securities		19,830		19,697
Investments- noncurrent	$	45,163	$	33,350

Marketable securities as of June 30, 2024 and December 31, 2023 consisted of the following (in thousands):

		June 30, 2024
		Cost or Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Marketable equity securities
Equity securities	$	58,530	$	5,868	$	(7,227	)	$	57,171
Marketable debt securities
U.S. treasury securities		64,816		976		(16	)		65,776
Corporate bonds		19,577		648		(395	)		19,830
Total marketable debt securities		84,393		1,624		(411	)		85,606
	$	142,923	$	7,492	$	(7,638	)	$	142,777

		December 31, 2023
		Cost or Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Marketable equity securities
Equity securities	$	59,228	$	7,896	$	(4,146	)	$	62,978
Marketable debt securities
U.S. treasury securities		53,662		1,307		(3	)		54,966
Corporate bonds		19,422		472		(197	)		19,697
Total marketable debt securities		73,084		1,779		(200	)		74,663
	$	132,312	$	9,675	$	(4,346	)	$	137,641

The amortized costs and fair value of our marketable debt securities, by contractual maturity, as of June 30, 2024 (in thousands) are as follows:

		June 30, 2024
		Amortized Cost		Fair Value
Less than 1 year	$	41,622	$	40,443
1 to 5 years		42,771		45,163
Total	$	84,393	$	85,606

As of June 30, 2024, the fair value of corporate bonds with unrealized loss position was $8.7 million, with an aggregated loss of $0.4 million. As June 30, 2024, the fair value of U.S. treasury securities with unrealized loss position was $6.6 million, with an aggregated loss of $16,000. As of December 31, 2023, the fair value of available-for-sale debt securities in unrealized loss position for corporate bonds and U.S. treasury securities were $7.1 million and $2.7 million, respectively, with an aggregated loss of $0.2 million. For all available-for-sale debt securities that were in unrealized loss positions, we have determined that it is more likely than not we will hold the securities until maturity or a recovery of the cost basis. We had no credit-related impairment loss as of June 30, 2024 and December 31, 2023.

Our derivative instruments consisted of call and put options sold at their fair value as of the balance sheet date. These derivative instruments are reported as Other current liabilities on our Condensed Consolidated Balance Sheets as of June 30, 2024 and December 31, 2023 (in thousands):

		June 30, 2024
		Cost		Unrealized Losses			Fair Value
Derivative instruments	$	6,131	$	(842	)	$	5,289
	$	6,131	$	(842	)	$	5,289

		December 31, 2023
		Cost		Unrealized Losses			Fair Value
Derivative instruments	$	8,797	$	(867	)	$	7,930
	$	8,797	$	(867	)	$	7,930

A summary of realized and unrealized gains and losses from our equity securities and derivative instruments and realized gains and losses from our marketable debt securities are as follows (in thousands):

		Three Months Ended June 30,						Six Months Ended June 30,
		2024			2023			2024			2023
Net unrealized gains (losses) recognized on marketable equity securities	$	(2,453	)	$	(1,255	)	$	(5,108	)	$	759
Net realized gains recognized on marketable equity securities		3,703			4,561			9,182			6,230
Net unrealized losses recognized on derivative instruments		(2,844	)		(91	)		(26	)		(194	)
Net realized gains recognized on derivative instruments		3,327			1,520			2,893			2,237
Net realized gains recognized on marketable debt securities		473			217			555			217
Total net gains recognized in interest and other income (loss), net	$	2,206		$	4,952		$	7,496		$	9,249

Our financial instruments include cash and cash equivalents, receivables, accrued liabilities and accounts payable. The fair value of cash and cash equivalents, receivables, accrued liabilities and accounts payable approximates their carrying values because of the short-term nature of these instruments, which are all considered Level 1. The fair value of long-term debt approximates its carrying value.

Our financial instruments measured at fair value on a recurring basis consisted of U.S. treasury securities, equity securities, corporate bonds and derivatives. U.S. treasury securities and equity securities are classified within Level 1 of the fair value hierarchy as they are valued based on quoted market price in an active market. Corporate bonds and derivative instruments are valued based on quoted prices in markets that are less active, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency are generally classified within Level 2 of the fair value hierarchy.

Financial instruments valued based on unobservable inputs which reflect the reporting entity’s own assumptions or data that market participants would use in valuing an instrument are generally classified within Level 3 of the fair value hierarchy. We did not hold Level 3 financial instruments as of June 30, 2024, and December 31, 2023.

Financial instruments measured at fair value on a recurring basis as of June 30, 2024 and December 31, 2023 are classified based on the valuation technique in the table below (in thousands):

		June 30, 2024
		Fair Value Measurements Using
		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
U.S. treasury securities	$	65,776	$	—	$	—	$	65,776
Equity securities		57,171		—		—		57,171
Corporate bonds		—		19,830		—		19,830
Total assets at fair value	$	122,947	$	19,830	$	—	$	142,777

Liabilities
Derivative instruments	$	—	$	5,289	$	—	$	5,289
Total liabilities at fair value	$	—	$	5,289	$	—	$	5,289

		December 31, 2023
		Fair Value Measurements Using
		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
U.S. treasury securities	$	54,966	$	—	$	—	$	54,966
Equity securities		62,977		—		—		62,977
Corporate bonds		—		19,697		—		19,697
Total assets at fair value	$	117,943	$	19,697	$	—	$	137,640

Liabilities
Derivative instruments	$	—	$	7,930	$	—	$	7,930
Total liabilities at fair value	$	—	$	7,930	$	—	$	7,930