Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionLetko, Brosseau & Associates Inc
Latest Disclosed Ownership358,019 shares
Latest Disclosed Value $ 43,066,106
Letko, Brosseau & Associates Inc reports 3.38% decrease in ownership of MRK / Merck & Co., Inc.

On May 12, 2026 - Letko, Brosseau & Associates Inc filed a 13F-HR form disclosing ownership of 358,019 shares of Merck & Co., Inc. (MX:MRK) valued at $43,066,106 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 11, 2026 disclosing 370,534 shares of Merck & Co., Inc.. This represents a change in shares of -3.38% 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)
2026-05-12 2026-03-31 13F MERCK COM 58933Y105 358,019 -12,515 -3.38 43,066 10.42 0.6941
2026-02-11 2025-12-31 13F MERCK COM 58933Y105 370,534 16,545 4.67 39,002 31.28 0.6386
2025-11-12 2025-09-30 13F MERCK COM 58933Y105 353,989 6,700 1.93 29,710 8.07 0.5103
2025-08-08 2025-06-30 13F MERCK COM 58933Y105 347,289 106,380 44.16 27,491 27.14 0.5259
2025-05-08 2025-03-31 13F MERCK COM 58933Y105 240,909 5,175 2.20 21,624 -7.79 0.4599
2025-02-14 2024-12-31 13F MERCK COM 58933Y105 235,734 3,425 1.47 23,451 -11.11 0.4532
2024-11-07 2024-09-30 13F MERCK COM 58933Y105 232,309 -1,930 -0.82 26,381 -9.02 0.4784
2024-08-06 2024-06-30 13F MERCK COM 58933Y105 234,239 -25,180 -9.71 28,999 -15.28 0.5499
2024-05-08 2024-03-31 13F MERCK COM 58933Y105 259,419 -2,030 -0.78 34,230 20.09 0.5950
2024-02-12 2023-12-31 13F MERCK COM 58933Y105 261,449 -7,760 -2.88 28,503 2.84 0.5191
2023-11-09 2023-09-30 13F MERCK COM 58933Y105 269,209 -3,090 -1.13 27,715 -11.79 0.5430
2023-08-10 2023-06-30 13F MERCK COM 58933Y105 272,299 -17,835 -6.15 31,421 1.79 0.5853
2023-05-11 2023-03-31 13F MERCK COM 58933Y105 290,134 -48,575 -14.34 30,867 -17.86 0.5770
2023-05-04 2022-12-31 13F/A-1 MERCK COM 58933Y105 338,709 -206,012 -37.82 37,580 -19.89 0.6771
2023-02-10 2022-12-31 13F MERCK COM 58933Y105 338,709 -206,012 38 0.0007
2022-11-10 2022-09-30 13F MERCK COM 58933Y105 544,721 -9,168 -1.66 46,911 -7.10 0.9303
2022-08-09 2022-06-30 13F MERCK COM 58933Y105 553,889 -85,870 -13.42 50,498 -3.80 0.8936
2022-05-11 2022-03-31 13F MERCK COM 58933Y105 639,759 -11,647 -1.79 52,492 5.14 0.7830
2022-02-09 2021-12-31 13F MERCK COM 58933Y105 651,406 -11,855 -1.79 49,924 0.21 0.7152
2021-11-03 2021-09-30 13F MERCK COM 58933Y105 663,261 -33,425 -4.80 49,818 -8.05 0.7212
2021-07-29 2021-06-30 13F MERCK COM 58933Y105 696,686 -6,280 -0.89 54,181 -0.02 0.7221
2021-05-11 2021-03-31 13F MERCK & CO. COM 58933Y105 702,966 -18,262 -2.53 54,192 -8.14 0.7394
2021-02-05 2020-12-31 13F MERCK & CO. COM 58933Y105 721,228 -70,435 -8.90 58,996 -10.16 0.8082
2020-11-09 2020-09-30 13F MERCK & CO. COM 58933Y105 791,663 -80,665 -9.25 65,668 -2.65 1.0217
2020-08-07 2020-06-30 13F MERCK & CO. COM 58933Y105 872,328 -52,050 -5.63 67,457 -5.15 0.9966
2020-05-14 2020-03-31 13F MERCK & CO. COM 58933Y105 924,378 -1,490 -0.16 71,122 -15.54 1.2196
2020-02-07 2019-12-31 13F MERCK COM 58933Y105 925,868 -54,555 -5.56 84,208 2.03 0.8391
2019-11-05 2019-09-30 13F MERCK COM 58933Y105 980,423 -55,560 -5.36 82,532 -4.99 0.8428
2019-08-01 2019-06-30 13F MERCK COM 58933Y105 1,035,983 -84,020 -7.50 86,867 -6.75 0.8747
2019-05-10 2019-03-31 13F MERCK COM 58933Y105 1,120,003 -82,002 -6.82 93,151 1.42 0.9289
2019-02-08 2018-12-31 13F MERCK COM 58933Y105 1,202,005 -370,213 -23.55 91,845 -17.65 1.0189
2018-11-08 2018-09-30 13F MERCK COM 58933Y105 1,572,218 -791,945 -33.50 111,533 -22.28 1.0370
2018-08-07 2018-06-30 13F MERCK COM 58933Y105 2,364,163 -36,575 -1.52 143,505 9.74 1.3131
2018-05-08 2018-03-31 13F MERCK COM 58933Y105 2,400,738 2,565 0.11 130,768 -3.10 1.2294
2018-02-20 2017-12-31 13F MERCK COM 58933Y105 2,398,173 -52,335 -2.14 134,945 -14.00 1.1842
2017-11-13 2017-09-30 13F MERCK COM 58933Y105 2,450,508 -9,400 -0.38 156,906 -0.48 1.4202
2017-08-10 2017-06-30 13F MERCK COM 58933Y105 2,459,908 -39,302 -1.57 157,656 -0.72 1.5416
2017-05-11 2017-03-31 13F MERCK COM 58933Y105 2,499,210 -64,219 -2.51 158,800 5.23 1.4870
2017-02-13 2016-12-31 13F MERCK COM 58933Y105 2,563,429 151,225 6.27 150,909 0.24 1.3840
2016-11-14 2016-09-30 13F MERCK COM 58933Y105 2,412,204 -68,450 -2.76 150,546 5.34 1.4079
2016-08-04 2016-06-30 13F MERCK COM 58933Y105 2,480,654 564,605 29.47 142,910 40.97 1.3629
2016-05-11 2016-03-31 13F MERCK & CO INC COM 58933Y105 1,916,049 -42,853 -2.19 101,378 -2.02 1.0001
2016-02-08 2015-12-31 13F MERCK & CO INC COM 58933Y105 1,958,902 486,575 33.05 103,469 42.29 1.0706
2015-11-12 2015-09-30 13F MERCK & CO INC COM 58933Y105 1,472,327 1,472,327 72,718 0.7405
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.