The gross carrying amounts and net book values of our intangible assets were as follows (in millions):


	March 31, 2026							December 31, 2025
	Remaining Weighted- Average Useful Life (In years)	Gross Carrying Amount		Accumulated Amortization		Net Book Value		Gross Carrying Amount		Accumulated Amortization		Net Book Value
Acquired developed technologies	6.6	$	8,092.6	$	(3,888.8)	$	4,203.8	$	8,194.6	$	(3,765.1)	$	4,429.5
Manufacturing contracts	—	1.3		(1.3)		—		12.6		(12.6)		—
Trademarks	—	2.9		(2.9)		—		2.9		(2.9)		—


Total finite-lived intangible assets		$	8,096.8	$	(3,893.0)	$	4,203.8	$	8,210.1	$	(3,780.6)	$	4,429.5

The decrease in the gross carrying amount of intangible assets as of March 31, 2026, compared to December 31, 2025, primarily relates to the negative impact of foreign currency translation adjustments primarily due to the weakening of sterling against the U.S. dollar.

The assumptions and estimates used to determine future cash flows and remaining useful lives of our intangible and other long-lived assets are complex and subjective. They can be affected by various factors, including external factors, such as industry and economic trends, and internal factors such as changes in our business strategy and our forecasts for specific product lines.

Based on finite-lived intangible assets recorded as of March 31, 2026, and assuming the underlying assets will not be impaired and that we will not change the expected lives of the assets, future amortization expenses were estimated as follows (in millions):


Year Ending December 31,	Estimated Amortization Expense
2026 (remainder)	$	505.4
2027	665.1
2028	641.2
2029	638.9
2030	578.5
Thereafter	1,174.7
Total	$	4,203.8