We estimate the fair values of our Level 1 financial instruments, which are in active markets, using unadjusted quoted market prices for identical instruments.

We obtain the fair values of our Level 2 financial instruments, which are not in active markets, from a primary professional pricing source that uses quoted market prices for identical or comparable instruments, rather than direct observations of quoted prices in active markets. Fair values obtained from this professional pricing source can also be based on pricing models whereby all significant observable inputs, including maturity dates, issue dates, settlement dates, benchmark yields, reported trades, broker-dealer quotes, issue spreads, benchmark securities, bids, offers or other market related data, are observable or can be derived from, or corroborated by, observable market data for substantially the full term of the asset.

We estimate the fair values of our Level 3 financial instruments based on unobservable inputs and other estimation techniques due to the absence of quoted market prices and inherent lack of liquidity.

The following table summarizes financial assets that we measured at fair value on a recurring basis as of June 30, 2025, classified in accordance with the fair value hierarchy:



	Fair Value Measurements Using
(In millions)	Level 1		Level 2		Level 3		Total
Cash equivalents	$	560.1	$	49.8	$	—	$	609.9

Debt securities, available-for-sale:
U.S. government agencies (1)	—		945.3		—		945.3
Commercial paper	—		143.7		—		143.7
Corporate debt	—		680.3		—		680.3

Total debt securities, available-for-sale	—		1,769.3		—		1,769.3

Other long-term assets:
Convertible notes receivable	—		—		11.1		11.1
Other assets (2)	19.7		—		—		19.7

Total assets measured at fair value on a recurring basis	$	579.8	$	1,819.1	$	11.1	$	2,410.0

The following table summarizes financial assets that we measured at fair value on a recurring basis as of December 31, 2024, classified in accordance with the fair value hierarchy:


	Fair Value Measurements Using
(In millions)	Level 1		Level 2		Level 3		Total
Cash equivalents	$	134.2	$	—	$	—	$	134.2

Debt securities, available-for-sale:
U.S. government agencies (1)	—		1,150.1		—		1,150.1
Commercial paper	—		312.1		—		312.1
Corporate debt	—		511.1		—		511.1

Total debt securities, available-for-sale	—		1,973.3		—		1,973.3

Other long-term assets:
Convertible notes receivable	—		—		10.5		10.5
Other assets (2)	20.6		—		—		20.6

Total assets measured at fair value on a recurring basis	$	154.8	$	1,973.3	$	10.5	$	2,138.6



	Fair Value Measurements Using Level 1
(In millions)	June 30, 2025		December 31, 2024
Senior Convertible Notes due 2025	$	1,187.2	$	1,163.7
Senior Convertible Notes due 2028	1,175.4		1,122.3
Total fair value of outstanding senior convertible notes	$	2,362.6	$	2,286.0

See Note 4 “Debt—Senior Convertible Notes” to the condensed consolidated financial statements for more information regarding the carrying values of our senior convertible notes.

As we conduct business globally in many currencies, we are exposed to foreign exchange rate changes. To limit this exposure, we enter into foreign currency forward contracts to hedge monetary assets and liabilities denominated in foreign currencies. Our foreign currency forward contracts are not designated as hedging instruments. Therefore, changes in the fair values of these contracts are recognized in earnings, thereby offsetting the current earnings effect of the related foreign currency assets and liabilities. The duration of these contracts is generally one month. The derivative gains and losses are included in other income, net in our condensed consolidated statements of operations.

As of June 30, 2025 and December 31, 2024, the notional amounts of outstanding foreign currency forward contracts were $56.6 million and $66.0 million, respectively. The resulting impact on our condensed consolidated financial statements from currency hedging activities was not significant for the three and six months ended June 30, 2025 and June 30, 2024.

We monitor the costs and the impact of foreign currency risks upon our financial results as part of our risk management program. We do not use derivative financial instruments for speculation or trading purposes or for activities other than risk management. We do not require and are not required to pledge collateral for these financial instruments and we do not carry any master netting arrangements to mitigate the credit risk.

In accordance with authoritative guidance, we measure certain non-financial assets and liabilities at fair value on a non-recurring basis. These measurements are usually performed using the discounted cash flow method or cost method and Level 3 inputs. These include items such as non-financial assets and liabilities initially measured at fair value in a business combination and non-financial long-lived assets measured at fair value for an impairment assessment. In general, non-financial assets, including goodwill, intangible assets, and property and equipment, are measured at fair value when there are indicators of impairment and are recorded at fair value only when an impairment is recognized.

We hold certain other investments that we do not measure at fair value on a recurring basis. The carrying values of these investments were $115.8 million as of June 30, 2025 and $119.3 million as of December 31, 2024. We include the carrying values of these investments in other assets in our condensed consolidated balance sheets. It is impracticable for us to estimate the fair value of these investments on a recurring basis due to the fact that these entities are privately held and limited information is available. We monitor the information that becomes available from time to time and adjust the carrying values of these investments if there are identified events or changes in circumstances that have a significant effect on the fair values.

There were no significant impairment losses on assets and liabilities measured at fair value on a non-recurring basis during the three and six months ended June 30, 2025 and June 30, 2024.