Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionGrandfield & Dodd, Llc
Latest Disclosed Ownership175,775 shares
Latest Disclosed Value $ 21,144,076
Grandfield & Dodd, Llc reports 4.59% increase in ownership of MRK / Merck & Co., Inc.

On May 7, 2026 - Grandfield & Dodd, Llc filed a 13F-HR form disclosing ownership of 175,775 shares of Merck & Co., Inc. (MX:MRK) valued at $21,144,076 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 10, 2026 disclosing 168,061 shares of Merck & Co., Inc.. This represents a change in shares of 4.59% 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)
2026-05-07 2026-03-31 13F MERCK COM 58933Y105 175,775 7,714 4.59 21,144 19.53 1.1938
2026-02-10 2025-12-31 13F MERCK COM 58933Y105 168,061 -16,228 -8.81 17,690 14.37 1.0019
2025-10-30 2025-09-30 13F MERCK COM 58933Y105 184,289 -8,679 -4.50 15,467 1.26 0.8774
2025-08-08 2025-06-30 13F MERCK COM 58933Y105 192,968 -35,972 -15.71 15,275 -25.67 0.8945
2025-05-02 2025-03-31 13F MERCK COM 58933Y105 228,940 -39,396 -14.68 20,550 -23.02 1.2741
2025-02-06 2024-12-31 13F MERCK COM 58933Y105 268,336 -16,716 -5.86 26,694 -17.53 1.6458
2024-11-08 2024-09-30 13F MERCK COM 58933Y105 285,052 -9,825 -3.33 32,371 -11.33 1.9182
2024-08-09 2024-06-30 13F MERCK COM 58933Y105 294,877 -10,502 -3.44 36,506 -9.40 2.3112
2024-05-06 2024-03-31 13F MERCK COM 58933Y105 305,379 -1,669 -0.54 40,295 20.37 2.5428
2024-01-31 2023-12-31 13F MERCK COM 58933Y105 307,048 -450 -0.15 33,474 5.74 2.3130
2023-10-26 2023-09-30 13F MERCK COM 58933Y105 307,498 -1,577 -0.51 31,657 -11.24 2.3258
2023-08-08 2023-06-30 13F MERCK COM 58933Y105 309,075 -3,272 -1.05 35,664 7.32 2.4931
2023-04-28 2023-03-31 13F MERCK COM 58933Y105 312,347 -1,269 -0.40 33,231 -4.50 2.3225
2023-01-20 2022-12-31 13F MERCK COM 58933Y105 313,616 808 0.26 34,796 29.16 2.5459
2022-11-04 2022-09-30 13F MERCK COM 58933Y105 312,808 2,338 0.75 26,940 -4.84 2.1995
2022-08-01 2022-06-30 13F MERCK COM 58933Y105 310,470 -303 -0.10 28,310 11.02 2.2298
2022-04-19 2022-03-31 13F MERCK COM 58933Y105 310,773 -947 -0.30 25,500 6.74 1.7305
2022-02-08 2021-12-31 13F MERCK COM 58933Y105 311,720 2,441 0.79 23,890 2.84 1.5368
2021-10-28 2021-09-30 13F MERCK COM 58933Y105 309,279 -4,274 -1.36 23,230 -4.76 1.6215
2021-07-28 2021-06-30 13F MERCK COM 58933Y105 313,553 7,171 2.34 24,390 3.26 1.6878
2021-04-22 2021-03-31 13F MERCK & CO. COM 58933Y105 306,382 -924 -0.30 23,620 -6.05 1.7659
2021-01-29 2020-12-31 13F MERCK & CO. COM 58933Y105 307,306 797 0.26 25,140 -1.10 1.9726
2020-11-03 2020-09-30 13F MERCK & CO. COM 58933Y105 306,509 -631 -0.21 25,420 7.03 2.2895
2020-07-24 2020-06-30 13F MERCK & CO. COM 58933Y105 307,140 -1,374 -0.45 23,750 0.05 2.2979
2020-05-14 2020-03-31 13F MERCK & CO. COM 58933Y105 308,514 -5,348 -1.70 23,737 -16.85 2.7988
2020-02-07 2019-12-31 13F MERCK COM 58933Y105 313,862 222 0.07 28,546 8.12 2.6005
2019-10-30 2019-09-30 13F MERCK COM 58933Y105 313,640 -669 -0.21 26,402 0.18 2.5978
2019-07-29 2019-06-30 13F MERCK COM 58933Y105 314,309 -15,081 -4.58 26,355 -3.80 2.6051
2019-04-26 2019-03-31 13F MERCK COM 58933Y105 329,390 -5,396 -1.61 27,395 7.09 2.8530
2019-02-12 2018-12-31 13F MERCK COM 58933Y105 334,786 -3,151 -0.93 25,581 6.71 3.0274
2018-11-02 2018-09-30 13F MERCK COM 58933Y105 337,937 -950 -0.28 23,973 16.54 2.4705
2018-07-27 2018-06-30 13F MERCK COM 58933Y105 338,887 -125 -0.04 20,570 11.39 2.2600
2018-05-04 2018-03-31 13F/A-1 MERCK COM 58933Y105 339,012 -5,270 -1.53 18,466 -4.68 2.0598
2018-05-04 2018-03-31 13F MERCK COM 58933Y105 339,012 -5,270 18,466
2018-02-05 2017-12-31 13F MERCK COM 58933Y105 344,282 659 0.19 19,373 -11.95 2.0680
2017-11-03 2017-09-30 13F MERCK COM 58933Y105 343,623 601 0.18 22,002 0.08 2.4701
2017-07-27 2017-06-30 13F MERCK COM 58933Y105 343,022 -1,750 -0.51 21,984 0.35 2.5977
2017-04-28 2017-03-31 13F MERCK COM 58933Y105 344,772 -3,014 -0.87 21,907 7.00 2.7058
2017-02-02 2016-12-31 13F MERCK COM 58933Y105 347,786 -1,229 -0.35 20,474 -6.00 2.6535
2016-10-24 2016-09-30 13F MERCK COM 58933Y105 349,015 -4,560 -1.29 21,782 6.94 2.8616
2016-07-28 2016-06-30 13F MERCK COM 58933Y105 353,575 1,096 0.31 20,369 9.22 2.8513
2016-05-06 2016-03-31 13F MERCK & CO INC COM 58933Y105 352,479 4,479 1.29 18,650 1.46 2.6990
2016-02-03 2015-12-31 13F MERCK & CO INC COM 58933Y105 348,000 9,183 2.71 18,381 9.84 2.7941
2015-11-02 2015-09-30 13F MERCK & CO INC COM 58933Y105 338,817 3,064 0.91 16,734 -12.45 2.8065
2015-08-03 2015-06-30 13F MERCK & CO INC COM 58933Y105 335,753 -3,375 -1.00 19,114 -1.94 2.9239
2015-05-15 2015-03-31 13F MERCK & CO INC COM 58933Y105 339,128 6,845 2.06 19,493 3.30 2.9799
2015-02-05 2014-12-31 13F MERCK & CO INC COM 58933Y105 332,283 -7,554 -2.22 18,870 -6.33 2.9167
2014-11-10 2014-09-30 13F MERCK & CO INC COM 58933Y105 339,837 -5,025 -1.46 20,146 0.98 3.1654
2014-08-14 2014-06-30 13F MERCK & CO INC COM 58933Y105 344,862 -1,809 -0.52 19,950 1.37 3.0098
2014-05-06 2014-03-31 13F MERCK & CO INC COM 58933Y105 346,671 4,713 1.38 19,681 14.99 3.0894
2014-02-06 2013-12-31 13F MERCK & CO INC COM 58933Y105 341,958 1,635 0.48 17,115 5.64 2.7808
2013-11-04 2013-09-30 13F MERCK & CO INC COM 58933Y105 340,323 -1,122 -0.33 16,202 2.16 2.8892
2013-08-01 2013-06-30 13F MERCK & CO INC COM 58933Y105 341,445 341,445 15,860 3.0040
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.