Regeneron Pharmaceuticals, Inc.
MX ˙ BMV ˙ US75886F1075
SecurityMX:REGN / Regeneron Pharmaceuticals, Inc.
InstitutionTamar Securities, LLC
Latest Disclosed Ownership35,199 shares
Latest Disclosed Value $ 27,196,300
Tamar Securities, LLC ownership in REGN / Regeneron Pharmaceuticals, Inc.

On May 14, 2026 - Tamar Securities, LLC filed a 13F-HR form disclosing ownership of 35,199 shares of Regeneron Pharmaceuticals, Inc. (MX:REGN) valued at $27,196,300 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 40,456 shares of Regeneron Pharmaceuticals, Inc.. This represents a change in shares of -12.99% during the quarter.

Tamar Securities, LLC has a history of taking positions in derivatives of the underlying security (REGN) in the form of stock options.

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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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

MX:REGN / Regeneron Pharmaceuticals, Inc. Historical Put/Call Ratio
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)
2026-05-14 2026-03-31 13F REGENERON PHARMACEUTICALS COM 75886F107 35,199 -5,257 -12.99 27,196 -12.91 2.9113
2026-02-13 2025-12-31 13F REGENERON PHARMACEUTICALS COM 75886F107 40,456 8,190 25.38 31,227 72.13 3.2960
2025-11-14 2025-09-30 13F REGENERON PHARMACEUTICALS COM 75886F107 32,266 1,885 6.20 18,142 13.75 2.0616
2025-08-11 2025-06-30 13F REGENERON PHARMACEUTICALS COM 75886F107 30,381 2,247 7.99 15,950 -10.61 1.9336
2025-05-15 2025-03-31 13F REGENERON PHARMACEUTICALS COM 75886F107 28,134 7,733 37.91 17,844 22.78 2.4175
2025-01-22 2024-12-31 13F REGENERON PHARMACEUTICALS COM 75886F107 20,401 4,909 31.69 14,532 -10.76 2.0043
2024-10-16 2024-09-30 13F REGENERON PHARMACEUTICALS COM 75886F107 15,492 2,211 16.65 16,286 16.67 2.2878
2024-10-10 2024-06-30 13F REGENERON PHARMACEUTICALS COM 75886F107 13,281 -731 -5.22 13,959 3.50 2.2626
2024-05-13 2024-03-31 13F REGENERON PHARMACEUTICALS COM 75886F107 14,012 -216 -1.52 13,486 7.92 2.2752
2024-01-25 2023-12-31 13F REGENERON PHARMACEUTICALS COM 75886F107 14,228 1,354 10.52 12,496 17.95 2.4523
2023-11-14 2023-09-30 13F REGENERON PHARMACEUTICALS COM 75886F107 12,874 -166 -1.27 10,595 13.08 2.5537
2024-10-10 2023-06-30 13F REGENERON PHARMACEUTICALS COM 75886F107 13,040 1,570 13.69 9,370 -0.58 2.3031
2024-10-10 2023-03-31 13F REGENERON PHARMACEUTICALS COM 75886F107 11,470 -1,180 -9.33 9,425 3.27 2.7065
2023-02-10 2022-12-31 13F REGENERON PHARMACEUTICALS COM 75886F107 12,650 -116 -0.91 9,127 3.78 2.8954
2022-11-07 2022-09-30 13F REGENERON PHARMACEUTICALS COM 75886F107 12,766 486 3.96 8,794 21.15 2.8133
2022-08-05 2022-06-30 13F REGENERON PHARMACEUTICALS COM 75886F107 12,280 319 2.67 7,259 -13.11 2.3830
2022-04-27 2022-03-31 13F REGENERON PHARMACEUTICALS COM 75886F107 11,961 1,358 12.81 8,354 24.76 2.3317
2022-02-14 2021-12-31 13F REGENERON PHARMACEUTICALS COM 75886F107 10,603 -152 -1.41 6,696 2.87 1.9731
2021-10-19 2021-09-30 13F REGENERON PHARMACEUTICALS COM 75886F107 10,755 -76 -0.70 6,509 7.59 2.3515
2021-08-06 2021-06-30 13F REGENERON PHARMACEUTICALS COM 75886F107 10,831 689 6.79 6,050 26.07 2.3289
2021-05-11 2021-03-31 13F REGENERON PHARMACEUTICALS COM 75886F107 10,142 1,904 23.11 4,799 20.58 1.8559
2021-01-27 2020-12-31 13F REGENERON PHARMACEUTICALS COM 75886F107 8,238 667 8.81 3,980 -6.09 2.2626
2020-11-05 2020-09-30 13F REGENERON PHARMACEUTICALS COM 75886F107 7,571 472 6.65 4,238 -4.27 2.6341
2020-09-10 2020-06-30 13F REGENERON PHARMACEUTICALS COM 75886F107 7,099 7,099 4,427 3.5276
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-14 2026-03-31 13F REGENERON PHARMACEUTICALS COM Call 77 n/a n/a n/a
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.