Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionBluefin Capital Management, Llc
Latest Disclosed Ownership4,000 shares
Latest Disclosed Value $ 481,160
Bluefin Capital Management, Llc ownership in MRK / Merck & Co., Inc.

On May 15, 2026 - Bluefin Capital Management, Llc filed a 13F-HR form disclosing ownership of 4,000 shares of Merck & Co., Inc. (MX:MRK) valued at $481,160 USD as of March 31, 2026. The entity filed a previous 13F-HR on November 14, 2023 disclosing 0 shares of Merck & Co., Inc..

Bluefin Capital Management, Llc has a history of taking positions in derivatives of the underlying security (MRK) in the form of stock options. The firm currently holds call options representing 0 of underlying shares valued at $0 USD and put options representing 0 of underlying shares valued at $0 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

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:MRK / Merck & Co., 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)
2026-05-15 2026-03-31 13F MERCK COM 58933Y105 4,000 4,000 481 0.2880
2023-11-14 2023-09-30 13F MERCK COM 58933Y105 0 -3,700 -100.00 0 -100.00
2023-09-11 2023-06-30 13F/A-1 MERCK COM 58933Y105 3,700 3,700 427 0.0815
2023-08-14 2023-06-30 13F MERCK COM 58933Y105 3,700 3,700 427 0.0838
2023-05-15 2023-03-31 13F MERCK COM 58933Y105 0 -29,300 -100.00 0 -100.00
2023-02-14 2022-12-31 13F MERCK COM 58933Y105 29,300 18,800 179.05 3,251 259.51 0.4831
2022-11-14 2022-09-30 13F MERCK COM 58933Y105 10,500 8,200 356.52 904 324.41 0.0817
2022-08-15 2022-06-30 13F MERCK COM 58933Y105 2,300 -2,600 -53.06 213 -47.01 0.0236
2022-05-16 2022-03-31 13F MERCK & CO. COM 58933Y105 4,900 -14,928 -75.29 402 -73.55 0.0367
2022-02-14 2021-12-31 13F MERCK COM 58933Y105 19,828 4,541 29.70 1,520 32.40 0.1061
2021-11-15 2021-09-30 13F MERCK COM 58933Y105 15,287 -39,834 -72.27 1,148 -73.22 0.1138
2021-08-18 2021-06-30 13F/A-1 MERCK COM 58933Y105 55,121 44,916 440.14 4,287 444.73 0.2725
2021-08-16 2021-06-30 13F MERCK COM 58933Y105 55,121 44,916 4,287 0.2725
2021-05-17 2021-03-31 13F MERCK & CO. COM 58933Y105 10,205 2,600 34.19 787 26.53 0.0367
2021-02-10 2020-12-31 13F MERCK & CO. COM 58933Y105 7,605 -2,600 -25.48 622 22.44 0.0363
2020-11-16 2020-09-30 13F MERCK & CO. COM 58933Y105 508 0.0324
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
(%)
2025-05-21 2025-03-31 13F MERCK COM Call 0 -100.00 0 n/a n/a n/a
2024-11-14 2024-09-30 13F MERCK COM Call 56,500 1 n/a n/a n/a
2024-05-20 2024-03-31 13F/A MERCK COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2024-05-15 2024-03-31 13F MERCK COM Call 0 0 n/a n/a n/a
2024-02-16 2023-12-31 13F MERCK COM Call 46,700 367.00 9 n/a n/a n/a
2023-11-14 2023-09-30 13F MERCK COM Call 10,000 0 n/a n/a n/a
2022-05-16 2022-03-31 13F MERCK COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2022-02-14 2021-12-31 13F MERCK COM Call 47,600 5 n/a n/a n/a
Disclosed Put 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
(%)
2023-05-15 2023-03-31 13F MERCK COM Put 0 -100.00 0 n/a n/a n/a
2023-02-14 2022-12-31 13F MERCK COM Put 17,500 0 n/a n/a n/a
2021-11-15 2021-09-30 13F MERCK COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2021-08-18 2021-06-30 13F/A MERCK COM Put 27,000 1 n/a n/a n/a
2021-08-16 2021-06-30 13F MERCK COM Put 27,000 1 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.