Regeneron Pharmaceuticals, Inc.
MX ˙ BMV ˙ US75886F1075
SecurityMX:REGN / Regeneron Pharmaceuticals, Inc.
InstitutionBoston Trust Walden Corp
Latest Disclosed Ownership1,193 shares
Latest Disclosed Value $ 921,760
Boston Trust Walden Corp reports 17.89% decrease in ownership of REGN / Regeneron Pharmaceuticals, Inc.

On April 24, 2026 - Boston Trust Walden Corp filed a 13F-HR form disclosing ownership of 1,193 shares of Regeneron Pharmaceuticals, Inc. (MX:REGN) valued at $921,760 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 28, 2026 disclosing 1,453 shares of Regeneron Pharmaceuticals, Inc.. This represents a change in shares of -17.89% 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)
2026-04-24 2026-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,193 -260 -17.89 922 -17.84 0.0045
2026-01-28 2025-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,453 0 0.00 1,122 37.38 0.0085
2025-10-17 2025-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,453 0 0.00 817 7.09 0.0060
2025-07-28 2025-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,453 0 0.00 763 -17.26 0.0054
2025-04-21 2025-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,453 0 0.00 922 -11.01 0.0067
2025-01-24 2024-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,453 0 0.00 1,035 -32.22 0.0073
2024-10-24 2024-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,453 -20 -1.36 1,527 -1.36 0.0106
2024-07-19 2024-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,473 0 0.00 1,548 9.24 0.0115
2024-04-22 2024-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,473 0 0.00 1,418 9.59 0.0101
2024-01-24 2023-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,473 0 0.00 1,294 6.68 0.0098
2023-10-18 2023-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,473 0 0.00 1,212 14.56 0.0102
2023-07-24 2023-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,473 0 0.00 1,058 -12.56 0.0087
2023-04-19 2023-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,473 165 12.61 1,210 28.31 0.0104
2023-01-20 2022-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,308 0 0.00 944 4.66 0.0083
2022-10-19 2022-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,308 0 0.00 901 16.56 0.0089
2022-07-22 2022-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,308 0 0.00 773 -15.43 0.0073
2022-04-20 2022-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,308 0 0.00 914 10.65 0.0075
2022-01-21 2021-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,308 0 0.00 826 4.29 0.0066
2021-10-25 2021-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,308 8 0.62 792 9.09 0.0070
2021-07-22 2021-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,300 0 0.00 726 18.05 0.0065
2021-04-21 2021-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,300 0 0.00 615 -2.07 0.0060
2021-01-15 2020-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,300 0 0.00 628 -13.74 0.0067
2020-10-14 2020-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,300 -12 -0.91 728 -11.00 0.0091
2020-07-23 2020-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,312 0 0.00 818 27.61 0.0110
2020-04-24 2020-03-31 13F/A-1 REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,312 -13 -0.98 641 28.71 0.0102
2020-04-21 2020-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,312 -13 641 5,683.9413
2020-01-10 2019-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,325 -125 -8.62 498 23.88 0.0058
2019-10-21 2019-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,450 0 0.00 402 -11.45 0.0051
2019-07-25 2019-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,450 0 0.00 454 -23.70 0.0059
2019-04-16 2019-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,450 0 0.00 595 9.78 0.0081
2019-01-17 2018-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,450 0 0.00 542 -7.51 0.0086
2018-10-23 2018-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,450 0 0.00 586 17.20 0.0081
2018-07-25 2018-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,450 250 20.83 500 21.07 0.0073
2018-04-13 2018-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,200 0 0.00 413 -8.43 0.0063
2018-01-29 2017-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,200 150 14.29 451 -3.84 0.0066
2017-10-13 2017-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,050 50 5.00 469 -4.48 0.0073
2017-07-19 2017-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 491 26.55 0.0079
2017-04-24 2017-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 388 5.72 0.0060
2017-02-07 2016-12-31 13F/A-1 REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 367 -8.71 0.0058
2017-02-01 2016-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 367
2016-10-17 2016-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 402 15.19 0.0066
2016-08-09 2016-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 349 -3.06 0.0060
2016-04-19 2016-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 360 -33.70 0.0063
2016-01-21 2015-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 543 16.77 0.0101
2015-10-29 2015-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 465 -8.82 0.0078
2015-07-17 2015-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 510 13.08 0.0078
2015-04-15 2015-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 1,000 0.00 451 0.0067
2015-01-28 2014-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 0 -1,000 -100.00 0 -100.00
2014-10-23 2014-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 361 28.01 0.0056
2014-08-01 2014-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 282 -6.00 0.0041
2014-04-11 2014-03-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 300 9.09 0.0045
2014-02-11 2013-12-31 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 275 -12.14 0.0040
2013-11-15 2013-09-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 0 0.00 313 39.11 0.0048
2013-08-08 2013-06-30 13F REGENERON PHARMACEUTICALS COMMON STOCK 75886F107 1,000 1,000 225 0.0036
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.