Adage Capital Partners Gp, L.l.c. reports 25.05% increase in ownership of REGN / Regeneron Pharmaceuticals, Inc.

Regeneron Pharmaceuticals, Inc.

MX ˙ BMV ˙ US75886F1075

Security	MX:REGN / Regeneron Pharmaceuticals, Inc.
Institution	Adage Capital Partners Gp, L.l.c.
Manager	Phil Gross, Robert Atchinson
Latest Disclosed Ownership	103,097 shares
Latest Disclosed Value	$ 79,656,866

On May 15, 2026 - Adage Capital Partners Gp, L.l.c. filed a 13F-HR form disclosing ownership of 103,097 shares of Regeneron Pharmaceuticals, Inc. (MX:REGN) valued at $79,656,866 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 82,446 shares of Regeneron Pharmaceuticals, Inc.. This represents a change in shares of 25.05% during the quarter.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)

File Date	Effective Date	Form	Security	Class	ID	Reported Shares	ΔShares	ΔShares (%)	Reported Value (x1000)	ΔValue (%)	Alloc (%)
2026-05-15	2026-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	103,097	20,651	25.05	79,657	25.17	0.1228
2026-02-17	2025-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	82,446	-40,600	-33.00	63,638	-8.02	0.0963
2025-11-14	2025-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	123,046	27,416	28.67	69,185	37.80	0.1096
2025-08-14	2025-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	95,630	2,885	3.11	50,206	-14.65	0.0846
2025-05-15	2025-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	92,745	48,396	109.13	58,822	86.20	0.1090
2025-02-14	2024-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	44,349	-125,290	-73.86	31,591	-82.29	0.0552
2024-11-14	2024-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	169,639	7,140	4.39	178,331	4.41	0.3149
2024-08-14	2024-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	162,499	30,361	22.98	170,791	34.29	0.3162
2024-05-15	2024-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	132,138	-3,511	-2.59	127,182	6.75	0.2401
2024-02-14	2023-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	135,649	40,900	43.17	119,139	52.79	0.2466
2023-11-14	2023-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	94,749	-43,300	-31.37	77,975	-21.39	0.1768
2023-08-14	2023-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	138,049	-35,200	-20.32	99,194	-30.32	0.2155
2023-05-15	2023-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	173,249	100,927	139.55	142,354	172.82	0.3193
2023-02-14	2022-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	72,322	10,073	16.18	52,180	21.68	0.1248
2022-11-14	2022-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	62,249	62,249		42,881		0.1064
2022-08-15	2022-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	0	-94,449	-100.00	0	-100.00
2022-05-16	2022-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	94,449	-1,200	-1.25	65,965	9.21	0.1253
2022-02-14	2021-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	95,649	165	0.17	60,404	4.53	0.1087
2021-11-15	2021-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	95,484	-1,222	-1.26	57,785	6.98	0.1138
2021-08-16	2021-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	96,706	48,300	99.78	54,014	135.84	0.1058
2021-05-17	2021-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	48,406	-52,200	-51.89	22,903	-52.88	0.0468
2021-02-16	2020-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	100,606	-1,130	-1.11	48,604	-14.65	0.1060
2020-11-16	2020-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	101,736	-49,150	-32.57	56,950	-39.48	0.1426
2020-08-14	2020-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	150,886	84,808	128.35	94,100	191.65	0.2409
2020-05-15	2020-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	66,078	66,078		32,265		0.0964
2019-05-15	2019-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	0	-37,021	-100.00	0	-100.00
2019-02-14	2018-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	37,021	-52,200	-58.51	13,827	-61.64	0.0383
2018-11-14	2018-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	89,221	89,221		36,049		0.0804
2018-02-14	2017-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	0	-11,910	-100.00	0	-100.00
2017-11-14	2017-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	11,910	-46,100	-79.47	5,325	-81.31	0.0129
2017-08-14	2017-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	58,010	58,010		28,491		0.0697
2017-05-15	2017-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	0	-13,310	-100.00	0	-100.00
2017-02-14	2016-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	13,310	-107,044	-88.94	4,886	-89.90	0.0133
2016-11-14	2016-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	120,354	75,180	166.42	48,385	206.70	0.1333
2016-08-15	2016-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	45,174	-6,100	-11.90	15,776	-14.64	0.0430
2016-05-16	2016-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	51,274	-64,930	-55.88	18,481	-70.70	0.0501
2016-02-16	2015-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	116,204	2,692	2.37	63,084	19.48	0.1653
2015-11-16	2015-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	113,512	48,600	74.87	52,799	59.45	0.1466
2015-08-14	2015-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	64,912	18,000	38.37	33,113	56.34	0.0826
2015-05-15	2015-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	46,912	-25,000	-34.76	21,180	-28.21	0.0516
2015-02-17	2014-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	71,912	27,132	60.59	29,502	82.74	0.0722
2014-11-14	2014-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	44,780	-194,300	-81.27	16,144	-76.09	0.0399
2014-08-14	2014-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	239,080	-63,600	-21.01	67,533	-25.70	0.1745
2014-05-15	2014-03-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	302,680	181,800	150.40	90,888	173.17	0.2482
2014-02-14	2013-12-31	13F	REGENERON PHARMACEUTICALS	COM	75886F107	120,880	-188,840	-60.97	33,271	-65.67	0.0881
2013-11-14	2013-09-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	309,720	14,950	5.07	96,902	46.18	0.2786
2013-08-14	2013-06-30	13F	REGENERON PHARMACEUTICALS	COM	75886F107	294,770	254,539	632.69	66,288	834.03	0.2044
2013-07-12	2013-03-31	13F/A-1	REGENERON PHARMACEUTICALS	COM	75886F107	40,231	40,231		7,097		0.0235

Legend

Shares: The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value: The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price: The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class: This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred

Allocation (%): The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation: The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%): The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis: The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss: This is the market value of the position as of the effective date minus the cost basis.