Regeneron Pharmaceuticals, Inc.
MX ˙ BMV ˙ US75886F1075
SecurityMX:REGN / Regeneron Pharmaceuticals, Inc.
InstitutionPenbrook Management LLC
Latest Disclosed Ownership785 shares
Latest Disclosed Value $ 606,522
Penbrook Management LLC reports 1.51% decrease in ownership of REGN / Regeneron Pharmaceuticals, Inc.

On April 21, 2026 - Penbrook Management LLC filed a 13F-HR form disclosing ownership of 785 shares of Regeneron Pharmaceuticals, Inc. (MX:REGN) valued at $606,522 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 6, 2026 disclosing 797 shares of Regeneron Pharmaceuticals, Inc.. This represents a change in shares of -1.51% 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 Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-04-21 2026-03-31 13F REGENERON PHARMACEUTICALS COM Stock 75886F107 785 -12 -1.51 607 -1.46 0.4593
2026-01-06 2025-12-31 13F REGENERON PHARMACEUTICALS COM Stock 75886F107 797 0 0.00 615 37.28 0.4243
2025-10-22 2025-09-30 13F REGENERON PHARMACEUTICALS COM Stock 75886F107 797 0 0.00 448 7.18 0.3129
2025-07-28 2025-06-30 13F/A-1 REGENERON PHARMACEUTICALS COM Stock 75886F107 797 -100 -11.15 418 -26.41 0.3146
2025-07-25 2025-06-30 13F REGENERON PHARMACEUTICALS Stock 75886F107 897 0 569 0.4300
2025-04-01 2025-03-31 13F REGENERON PHARMACEUTICALS Stock 75886F107 897 0 0.00 569 -10.97 0.4300
2025-01-23 2024-12-31 13F REGENERON PHARMACEUTICALS Stock 75886F107 897 -250 -21.80 639 -47.05 0.4359
2024-10-15 2024-09-30 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,147 0 0.00 1,206 0.00 0.7839
2024-07-24 2024-06-30 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,147 0 0.00 1,206 9.25 0.7358
2024-04-18 2024-03-31 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,147 0 0.00 1,104 9.53 0.6842
2024-01-16 2023-12-31 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,147 100 9.55 1,007 16.96 0.6768
2023-10-10 2023-09-30 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,047 25 2.45 862 17.30 0.6314
2023-07-17 2023-06-30 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,022 -50 -4.66 734 -16.59 0.5322
2023-04-20 2023-03-31 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,072 0 0.00 881 13.84 0.6749
2023-01-24 2022-12-31 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,072 -200 -15.72 773 -11.76 0.6592
2022-10-31 2022-09-30 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,272 0 0.00 876 16.49 0.7539
2022-07-29 2022-06-30 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,272 0 0.00 752 -15.32 0.5930
2022-04-26 2022-03-31 13F REGENERON PHARMACEUTICALS COM Stock 75886F107 1,272 0 0.00 888 10.59 0.5761
2022-01-10 2021-12-31 13F REGENERON PHARMACEUTICALS Stock 75886F107 1,272 0 0.00 803 4.29 0.4838
2021-10-26 2021-09-30 13F REGENERON PHARMACEUTICALS COM Stock 75886F107 1,272 0 0.00 770 8.45 0.4785
2021-07-27 2021-06-30 13F REGENERON PHARMACEUTICALS COM COM 75886F107 1,272 462 57.04 710 85.38 0.4256
2021-05-06 2021-03-31 13F/A-2 REGENERON PHARMACEUTICALS Stock 75886F107 810 710 710.00 383 697.92 0.2756
2021-05-05 2021-03-31 13F/A-1 REGENERON PHARMACEUTICALS Stock 75886F107 810 0 383 0.2778
2021-01-27 2020-12-31 13F REGENERON PHARMACEUTICALS COM 75886F107 100 100 48 0.0338
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.