Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionBoothbay Fund Management, Llc
Latest Disclosed Ownership25,244 shares
Latest Disclosed Value $ 3,036,601
Boothbay Fund Management, Llc ownership in MRK / Merck & Co., Inc.

On May 15, 2026 - Boothbay Fund Management, Llc filed a 13F-HR form disclosing ownership of 25,244 shares of Merck & Co., Inc. (MX:MRK) valued at $3,036,601 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 5,646 shares of Merck & Co., Inc.. This represents a change in shares of 347.11% during the quarter.

Boothbay Fund 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 25,244 19,598 347.11 3,037 411.11 0.0394
2026-02-17 2025-12-31 13F MERCK COM 58933Y105 5,646 -13,923 -71.15 594 -63.82 0.0089
2025-11-14 2025-09-30 13F MERCK COM 58933Y105 19,569 8,064 70.09 1,642 80.44 0.0239
2025-08-14 2025-06-30 13F MERCK COM 58933Y105 11,505 11,505 911 0.0177
2025-05-15 2025-03-31 13F MERCK COM 58933Y105 0 -7,905 -100.00 0 -100.00
2025-02-14 2024-12-31 13F MERCK COM 58933Y105 7,905 7,905 786 0.0194
2024-11-14 2024-09-30 13F MERCK COM 58933Y105 0 -52,426 -100.00 0 -100.00
2024-08-14 2024-06-30 13F MERCK COM 58933Y105 52,426 19,572 59.57 6,490 49.71 0.1537
2024-05-15 2024-03-31 13F MERCK COM 58933Y105 32,854 -181,426 -84.67 4,335 -81.44 0.0835
2024-02-14 2023-12-31 13F MERCK COM 58933Y105 214,280 11,638 5.74 23,361 11.98 0.5962
2023-11-14 2023-09-30 13F MERCK COM 58933Y105 202,642 83,119 69.54 20,862 51.27 0.4956
2023-08-14 2023-06-30 13F MERCK COM 58933Y105 119,523 -101,737 -45.98 13,792 -41.41 0.3025
2023-05-15 2023-03-31 13F MERCK COM 58933Y105 221,260 144,419 187.95 23,540 176.12 0.4829
2023-02-14 2022-12-31 13F MERCK COM 58933Y105 76,841 -55,146 -41.78 8,526 -25.00 0.1973
2022-11-14 2022-09-30 13F MERCK COM 58933Y105 131,987 53,921 69.07 11,367 59.72 0.2838
2022-08-15 2022-06-30 13F MERCK COM 58933Y105 78,066 -23,299 -22.99 7,117 -14.43 0.1873
2022-05-16 2022-03-31 13F MERCK COM 58933Y105 101,365 95,813 1,725.74 8,317 1,852.35 0.1934
2022-02-14 2021-12-31 13F MERCK COM 58933Y105 5,552 1,221 28.19 426 31.08 0.0100
2021-11-15 2021-09-30 13F MERCK COM 58933Y105 4,331 -28,572 -86.84 325 -87.30 0.0090
2021-08-17 2021-06-30 13F/A-1 MERCK COM 58933Y105 32,903 -62,595 -65.55 2,559 -65.24 0.0822
2021-08-16 2021-06-30 13F MERCK COM 58933Y105 32,903 -62,595 2,559 0.0805
2021-05-17 2021-03-31 13F MERCK & CO. COM 58933Y105 95,498 36,419 61.64 7,362 52.33 0.2758
2021-02-12 2020-12-31 13F MERCK & CO. COM 58933Y105 59,079 38,805 191.40 4,833 187.34 0.1799
2020-11-16 2020-09-30 13F MERCK & CO. COM 58933Y105 20,274 15,597 333.48 1,682 364.64 0.1018
2020-08-14 2020-06-30 13F MERCK & CO. COM 58933Y105 4,677 -4,070 -46.53 362 -46.21 0.0248
2020-05-15 2020-03-31 13F MERCK & CO. COM 58933Y105 8,747 -25,597 -74.53 673 -78.46 0.0558
2020-02-14 2019-12-31 13F MERCK COM 58933Y105 34,344 3,005 9.59 3,124 18.42 0.2718
2019-11-14 2019-09-30 13F Merck COM 58933Y105 31,339 31,339 2,638 0.2419
2019-05-15 2019-03-31 13F MERCK PUT 58933Y955 0 -94 -100.00 0 -100.00
2019-02-14 2018-12-31 13F MERCK PUT 58933Y955 94 94 718 0.1046
2018-08-14 2018-06-30 13F MERCK COM 58933Y105 0 -6,149 -100.00 0 -100.00
2018-05-14 2018-03-31 13F MERCK COM 58933Y105 6,149 6,149 335 0.0397
2017-11-14 2017-09-30 13F MERCK COM 58933Y105 0 -4,087 -100.00 0 -100.00
2017-08-14 2017-06-30 13F MERCK COM 58933Y105 4,087 -338 -7.64 262 -6.76 0.0545
2017-05-15 2017-03-31 13F Merck COM 58933Y105 4,425 -7,818 -63.86 281 -61.03 0.0524
2017-07-18 2016-12-31 13F/A-2 Merck COM 58933Y105 12,243 2,470 25.27 721 0.00 0.1642
2017-02-16 2016-12-31 13F/A-1 MERCK COM 58933Y105 12,243 0 721 0.1780
2017-02-15 2016-12-31 13F MERCK COM 58933Y105 12,243 721
2016-11-14 2016-09-30 13F Merck EQUITIES 58933Y105 9,773 9,773 1 0.1897
2016-06-09 2015-09-30 13F/A-1 MERCK & CO INC COM 58933Y105 0 -4,668 -100.00 0 -100.00
2016-06-09 2015-06-30 13F/A-2 MERCK & CO INC COM 58933Y105 4,668 -540 -10.37 266 -11.04 0.2601
2015-08-17 2015-06-30 13F/A-1 MERCK & CO INC COM 58933Y105 4,510 -158 257 0.1069
2015-08-14 2015-06-30 13F MERCK & CO INC COM 58933Y105 4,510 257
2016-06-09 2015-03-31 13F/A-2 MERCK & CO INC COM 58933Y105 5,208 5,208 299 0.4258
2015-06-10 2015-03-31 13F/A-1 MERCK &CO INC COM 58933Y105 4,666 -542 268 0.3064
2015-05-15 2015-03-31 13F MERCK &CO INC COM 58933Y105 4,666 268 0.2701
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
(%)
2023-05-15 2023-03-31 13F MERCK COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2023-02-14 2022-12-31 13F MERCK COM Call 36,100 607.84 4,005 812.30 n/a n/a n/a
2022-11-14 2022-09-30 13F MERCK COM Call 5,100 -95.99 439 -96.21 n/a n/a n/a
2022-08-15 2022-06-30 13F MERCK COM Call 127,100 1,133.98 11,588 1,271.36 n/a n/a n/a
2022-05-16 2022-03-31 13F MERCK COM Call 10,300 845 n/a n/a n/a
2022-02-14 2021-12-31 13F MERCK COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2021-11-15 2021-09-30 13F MERCK COM Call 585,800 43,999 n/a n/a n/a
2020-02-14 2019-12-31 13F MRK 11 CALL Call 0 -100.00 0 -100.00 n/a n/a n/a
2019-11-14 2019-09-30 13F MRK 11 CALL Call 192 1,616 n/a n/a n/a
2018-11-14 2018-09-30 13F MERCK CALL Call 0 -100.00 0 -100.00 n/a n/a n/a
2018-08-14 2018-06-30 13F MERCK CALL Call 315 1,912 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
(%)
2023-08-14 2023-06-30 13F MERCK COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2023-05-15 2023-03-31 13F MERCK COM Put 71,300 7,586 n/a n/a n/a
2023-02-14 2022-12-31 13F MERCK COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2022-11-14 2022-09-30 13F MERCK COM Put 5,300 -95.91 456 -96.14 n/a n/a n/a
2022-08-15 2022-06-30 13F MERCK COM Put 129,700 1,112.15 11,825 1,246.81 n/a n/a n/a
2022-05-16 2022-03-31 13F MERCK COM Put 10,700 878 n/a n/a n/a
2019-05-15 2019-03-31 13F MERCK PUT 0 -100.00 0 -100.00 n/a n/a n/a
2019-02-14 2018-12-31 13F MERCK PUT 94 718 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.