Available-for-sale debt securities are recorded at fair value, with the portion of the unrealized gains and losses that are not credit-related included as a component of accumulated other comprehensive (loss) income in stockholders’ equity, until realized. Available-for-sale debt securities consisted of the following (in millions):


As of March 31, 2026	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. government and agency securities	$	1,723.3	$	2.7	$	(3.3)	$	1,722.7
Corporate debt securities	403.5		0.7		(0.8)		403.4

Total	$	2,126.8	$	3.4	$	(4.1)	$	2,126.1


Reported under the following captions in our consolidated balance sheets:
Cash and cash equivalents	$	—
Current marketable investments	808.7
Non-current marketable investments	1,317.4
Total	$	2,126.1


As of December 31, 2025	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. government and agency securities	$	2,433.0	$	10.5	$	(0.3)	$	2,443.2
Corporate debt securities	603.1		3.7		—		606.8

Total	$	3,036.1	$	14.2	$	(0.3)	$	3,050.0


Reported under the following captions in our consolidated balance sheets:
Cash and cash equivalents	$	37.0
Current marketable investments	1,236.3
Non-current marketable investments	1,776.7
Total	$	3,050.0

The following tables present gross unrealized losses and fair value for those available-for-sale debt securities that were in an unrealized loss position as of March 31, 2026 and December 31, 2025, aggregated by investment category and length of time that the individual securities have been in a continuous loss position (in millions):


	Less than 12 months				12 months or longer				Total
As of March 31, 2026	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. government and agency securities	$	822.6	$	(3.3)	$	—	$	—	$	822.6	$	(3.3)
Corporate debt securities	119.6		(0.8)		—		—		119.6		(0.8)
Total	$	942.2	$	(4.1)	$	—	$	—	$	942.2	$	(4.1)


	Less than 12 months				12 months or longer				Total
As of December 31, 2025	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. government and agency securities	$	215.0	$	(0.3)	$	3.5	$	—	$	218.5	$	(0.3)
Corporate debt securities	19.6		—		—		—		19.6		—
Total	$	234.6	$	(0.3)	$	3.5	$	—	$	238.1	$	(0.3)

As of March 31, 2026 and December 31, 2025, we held 98 and 87 available-for-sale debt securities, respectively, that were in an unrealized loss position. In assessing whether the decline in fair value as of March 31, 2026 of any of these securities resulted from a credit loss, we consulted with our investment managers and reviewed the credit ratings for each security. We believe that these unrealized losses are a direct result of the current interest rate environment and do not represent an indication of credit loss. We do not intend to sell the investments in unrealized loss positions prior to their maturity, and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost basis. There were no impairments due to credit loss on our available-for-sale debt securities during the three months ended March 31, 2026 and 2025.

The following table summarizes the contractual maturities of available-for-sale debt securities (in millions). Actual maturities may differ from contractual maturities because the issuers of certain of these debt securities have the right to call the securities or prepay their obligations under the securities with or without penalties.

We held investments in equity securities with readily determinable fair values, in the aggregate, of $65.3 million and $126.9 million as of March 31, 2026 and December 31, 2025, respectively, which are included in current marketable investments in our consolidated balance sheets. Changes in the fair value of publicly traded equity securities are recorded in our consolidated statements of operations within other expense, net. See Note 4—Fair Value Measurements.

As of March 31, 2026 and December 31, 2025, we maintained non-controlling equity investments in privately held companies of $91.6 million and $53.8 million, respectively. We invested $25.0 million and zero in privately held companies during the three months ended March 31, 2026 and March 31, 2025, respectively. We measure these investments using the measurement alternative because the fair values of these investments are not readily determinable. Under this alternative, the investments are measured at cost, less any impairment, and adjusted for any observable price changes. We include our investments in privately held companies within other non-current assets in our consolidated balance sheets.

When an observable price transaction occurs that is identified as similar or identical to our investment, we perform a valuation analysis to assess the fair value of our investment using various inputs, such as the discount rate, time to a liquidation event, and price volatility of peer company stocks. We adjust the fair value of our investment based on the valuation analysis and recognize the gain or loss in the period in which the observable price change occurred. During the three months ended March 31, 2026, one of the privately held companies in which we invested raised additional capital by issuing equity securities similar to ours at an increased valuation compared to prior financing rounds, which resulted in an increase of $12.8 million in the value of our investment. This gain was recorded within other expense, net in our consolidated statements of operations.

These investments are subject to a periodic impairment review and, if impaired, the investment is measured and recorded at fair value in accordance with ASC 820, Fair Value Measurements.

For non-controlling equity investments in privately held companies in which we held an investment as of March 31, 2026, cumulative impairments and downward fair value adjustments were $5.3 million and cumulative upward fair value adjustments were $14.8 million.