Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionHemenway Trust Co LLC
Latest Disclosed Ownership6,880 shares
Latest Disclosed Value $ 827,595
Hemenway Trust Co LLC reports 3.10% decrease in ownership of MRK / Merck & Co., Inc.

On May 7, 2026 - Hemenway Trust Co LLC filed a 13F-HR form disclosing ownership of 6,880 shares of Merck & Co., Inc. (MX:MRK) valued at $827,595 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 3, 2026 disclosing 7,100 shares of Merck & Co., Inc.. This represents a change in shares of -3.10% 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 6,880 -220 -3.10 828 10.71 0.0666
2026-02-03 2025-12-31 13F MERCK COM 58933Y105 7,100 -605 -7.85 747 15.63 0.0572
2025-11-07 2025-09-30 13F MERCK COM 58933Y105 7,705 -957 -11.05 647 -5.69 0.0495
2025-07-23 2025-06-30 13F MERCK COM 58933Y105 8,662 -567 -6.14 686 -17.27 0.0531
2025-04-18 2025-03-31 13F MERCK COM 58933Y105 9,229 -695 -7.00 828 -16.11 0.0674
2025-02-13 2024-12-31 13F MERCK COM 58933Y105 9,924 568 6.07 987 -7.06 0.0801
2024-11-05 2024-09-30 13F MERCK COM 58933Y105 9,356 174 1.90 1,062 -6.51 0.0840
2024-08-05 2024-06-30 13F MERCK COM 58933Y105 9,182 -41 -0.44 1,137 -6.58 0.0973
2024-05-06 2024-03-31 13F MERCK COM 58933Y105 9,223 394 4.46 1,217 26.40 0.1054
2024-02-13 2023-12-31 13F MERCK COM 58933Y105 8,829 -11,177 -55.87 963 -53.28 0.0920
2023-11-14 2023-09-30 13F MERCK COM 58933Y105 20,006 -75 -0.37 2,060 -11.14 0.2159
2023-08-11 2023-06-30 13F MERCK COM 58933Y105 20,081 -940 -4.47 2,317 3.62 0.2273
2023-05-10 2023-03-31 13F MERCK COM 58933Y105 21,021 1,088 5.46 2,236 1.13 0.2370
2023-02-08 2022-12-31 13F MERCK COM 58933Y105 19,933 131 0.66 2,212 29.68 0.2459
2022-11-08 2022-09-30 13F MERCK COM 58933Y105 19,802 739 3.88 1,705 -1.90 0.2003
2022-07-19 2022-06-30 13F MERCK COM 58933Y105 19,063 -3,042 -13.76 1,738 -4.19 0.1978
2022-05-16 2022-03-31 13F MERCK COM 58933Y105 22,105 30 0.14 1,814 7.21 0.1743
2022-02-08 2021-12-31 13F MERCK COM 58933Y105 22,075 1,029 4.89 1,692 7.02 0.1541
2021-11-10 2021-09-30 13F MERCK COM 58933Y105 21,046 -675 -3.11 1,581 -6.39 0.1597
2021-08-09 2021-06-30 13F MERCK COM 58933Y105 21,721 1,096 5.31 1,689 6.23 0.1703
2021-05-17 2021-03-31 13F MERCK COM 58933Y105 20,625 -356 -1.70 1,590 -7.34 0.1739
2021-02-16 2020-12-31 13F MERCK COM 58933Y105 20,981 308 1.49 1,716 0.06 0.1964
2020-10-28 2020-09-30 13F MERCK COM 58933Y105 20,673 -629 -2.95 1,715 4.13 0.2229
2020-07-28 2020-06-30 13F MERCK COM 58933Y105 21,302 686 3.33 1,647 3.85 0.2290
2020-05-07 2020-03-31 13F MERCK COM 58933Y105 20,616 479 2.38 1,586 -13.38 0.2681
2020-01-15 2019-12-31 13F MERCK COM 58933Y105 20,137 -6,376 -24.05 1,831 -17.97 0.2633
2019-11-04 2019-09-30 13F MERCK COM 58933Y105 26,513 -3,580 -11.90 2,232 -11.53 0.3497
2019-07-24 2019-06-30 13F MERCK COM 58933Y105 30,093 -3,229 -9.69 2,523 -8.95 0.3896
2019-04-29 2019-03-31 13F/A-1 MERCK COM 58933Y105 33,322 -2,415 -6.76 2,771 1.46 0.4468
2019-04-29 2019-03-31 13F MERCK COM 58933Y105 33,322 2,771
2019-01-24 2018-12-31 13F MERCK COM 58933Y105 35,737 -2,000 -5.30 2,731 2.02 0.5577
2018-10-15 2018-09-30 13F MERCK COM 58933Y105 37,737 1,590 4.40 2,677 22.01 0.4510
2018-07-30 2018-06-30 13F MERCK COM 58933Y105 36,147 -15,897 -30.55 2,194 -22.61 0.4050
2018-04-24 2018-03-31 13F MERCK COM 58933Y105 52,044 840 1.64 2,835 -1.60 0.5394
2018-02-02 2017-12-31 13F MERCK COM 58933Y105 51,204 -4,493 -8.07 2,881 -19.21 0.5488
2017-10-26 2017-09-30 13F MERCK COM 58933Y105 55,697 100 0.18 3,566 0.08 0.7444
2017-07-21 2017-06-30 13F MERCK COM 58933Y105 55,597 -929 -1.64 3,563 -0.81 0.7922
2017-05-15 2017-03-31 13F MERCK COM 58933Y105 56,526 2,820 5.25 3,592 13.60 0.8271
2017-02-10 2016-12-31 13F MERCK Common Stock 58933Y105 53,706 -6,264 -10.45 3,162 -15.52 0.7974
2016-11-14 2016-09-30 13F MERCK Common Stock 58933Y105 59,970 -133 -0.22 3,743 8.09 0.9368
2016-08-08 2016-06-30 13F MERCK Common Stock 58933Y105 60,103 -620 -1.02 3,463 7.78 0.9030
2016-05-27 2016-03-31 13F MERCK Common Stock 58933Y105 60,723 -1,100 -1.78 3,213 -1.59 0.8673
2016-02-08 2015-12-31 13F MERCK Common Stock 58933Y105 61,823 33 0.05 3,265 6.98 0.8617
2015-11-13 2015-09-30 13F MERCK Common Stock 58933Y105 61,790 120 0.19 3,052 -13.07 0.8430
2015-07-31 2015-06-30 13F MERCK Common Stock 58933Y105 61,670 -120 -0.19 3,511 -1.15 0.9011
2015-05-22 2015-03-31 13F MERCK Common Stock 58933Y105 61,790 6,345 11.44 3,552 12.80 0.9301
2015-02-13 2014-12-31 13F MERCK Common Stock 58933Y105 55,445 760 1.39 3,149 -2.87 0.9414
2014-11-24 2014-09-30 13F MERCK Common Stock 58933Y105 54,685 -6,000 -9.89 3,242 -7.66 1.0140
2014-07-23 2014-06-30 13F MERCK Common Stock 58933Y105 60,685 1,403 2.37 3,511 4.34 1.0652
2014-05-23 2014-03-31 13F MERCK Common Stock 58933Y105 59,282 519 0.88 3,365 14.42 1.0594
2014-02-27 2013-12-31 13F MERCK Common Stock 58933Y105 58,763 1,763 3.09 2,941 8.36 0.9433
2013-11-18 2013-09-30 13F MERCK Common Stock 58933Y105 57,000 0 0.00 2,714 2.49 1.0117
2013-08-19 2013-06-30 13F MERCK Common Stock 58933Y105 57,000 0 0.00 2,648 5.12 1.1292
2013-05-24 2013-03-31 13F MERCK Common Stock 58933Y105 57,000 57,000 2,519 1.0662
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.