Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionGreat Lakes Advisors, Llc
Latest Disclosed Ownership1,569,387 shares
Latest Disclosed Value $ 188,782,026
Great Lakes Advisors, Llc reports 6.42% decrease in ownership of MRK / Merck & Co., Inc.

On May 11, 2026 - Great Lakes Advisors, Llc filed a 13F-HR form disclosing ownership of 1,569,387 shares of Merck & Co., Inc. (MX:MRK) valued at $188,782,026 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 12, 2026 disclosing 1,677,111 shares of Merck & Co., Inc.. This represents a change in shares of -6.42% 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)
2026-05-11 2026-03-31 13F Merck COM 58933Y105 1,569,387 -107,724 -6.42 188,782 6.94 0.4590
2026-02-12 2025-12-31 13F Merck and COM 58933Y105 1,677,111 39,268 2.40 176,533 28.42 1.4394
2025-11-03 2025-09-30 13F Merck and COM 58933Y105 1,637,843 -17,692 -1.07 137,465 4.89 1.1474
2025-08-11 2025-06-30 13F Merck COM 58933Y105 1,655,535 500,576 43.34 131,052 26.65 1.0983
2025-05-16 2025-03-31 13F Merck COM 58933Y105 1,154,959 13,648 1.20 103,478 -8.86 0.9256
2025-02-10 2024-12-31 13F Merck and COM 58933Y105 1,141,311 7,549 0.67 113,538 -11.82 0.9711
2024-11-04 2024-09-30 13F Merck and COM 58933Y105 1,133,762 -81,062 -6.67 128,750 -14.39 1.0780
2024-08-06 2024-06-30 13F Merck and COM 58933Y105 1,214,824 -258,293 -17.53 150,395 -22.63 1.3344
2024-05-08 2024-03-31 13F Merck and COM 58933Y105 1,473,117 442,237 42.90 194,378 72.95 1.6484
2024-02-08 2023-12-31 13F Merck and COM 58933Y105 1,030,880 -31,788 -2.99 112,387 2.73 1.0707
2023-11-07 2023-09-30 13F Merck and COM 58933Y105 1,062,668 37,135 3.62 109,402 -7.55 0.9963
2023-08-10 2023-06-30 13F Merck and COM 58933Y105 1,025,533 -136,927 -11.78 118,336 -4.32 1.1823
2023-05-10 2023-03-31 13F Merck and COM 58933Y105 1,162,460 548,448 89.32 123,674 1,395.27 1.1237
2023-02-09 2022-12-31 13F Merck and COM 58933Y105 614,012 -129,236 -17.39 8,271 -87.08 0.4739
2022-11-09 2022-09-30 13F Merck and COM 58933Y105 743,248 -24,901 -3.24 64,009 -8.60 1.3974
2022-08-09 2022-06-30 13F Merck and COM 58933Y105 768,149 28,037 3.79 70,033 15.32 1.3846
2022-05-06 2022-03-31 13F Merck and COM 58933Y105 740,112 -19,508 -2.57 60,727 4.31 0.7761
2022-05-06 2022-03-31 13F Merck and COM 58933Y105 720,200 59,093
2022-02-09 2021-12-31 13F Merck and COM 58933Y105 759,620 -24,938 -3.18 58,217 -1.21 0.8860
2021-11-09 2021-09-30 13F Merck COM 58933Y105 784,558 -2,190 -0.28 58,928 -3.69 0.9188
2021-08-11 2021-06-30 13F Merck COM 58933Y105 786,748 57,244 7.85 61,186 8.80 0.9230
2021-05-03 2021-03-31 13F Merck COM 58933Y105 729,504 147,017 25.24 56,238 18.03 0.9086
2021-02-09 2020-12-31 13F Merck COM 58933Y105 582,487 29,541 5.34 47,647 3.88 0.8624
2020-11-04 2020-09-30 13F Merck COM 58933Y105 552,946 5,097 0.93 45,868 8.27 0.9705
2020-08-07 2020-06-30 13F Merck COM 58933Y105 547,849 -68,479 -11.11 42,365 -10.66 1.0278
2020-05-08 2020-03-31 13F Merck COM 58933Y105 616,328 -14,133 -2.24 47,420 -17.30 1.3843
2020-02-07 2019-12-31 13F Merck COM 58933Y105 630,461 -133,080 -17.43 57,340 -10.79 1.2308
2019-11-06 2019-09-30 13F Merck COM 58933Y105 763,541 -30,665 -3.86 64,274 -3.48 1.4115
2019-08-05 2019-06-30 13F Merck COM 58933Y105 794,206 190,326 31.52 66,593 32.59 1.4513
2019-05-07 2019-03-31 13F Merck COM 58933Y105 603,880 -297,162 -32.98 50,224 -27.05 1.1174
2019-02-13 2018-12-31 13F Merck COM 58933Y105 901,042 -300,222 -24.99 68,849 -19.21 1.6312
2018-11-30 2018-09-30 13F/A-2 Merck COM 58933Y105 1,201,264 53,148 4.63 85,218 22.28 1.8805
2018-11-15 2018-09-30 13F/A-1 MERCK CO INC COM 58933Y105 11,660 -1,189,604 827 0.1348
2018-11-14 2018-09-30 13F MERCK N CO INC COM 58933Y105 1,148,116 0 69,691
2018-08-13 2018-06-30 13F MERCK N CO INC COM 58933Y105 1,148,116 -226,136 -16.46 69,691 4.86 1.6336
2018-05-07 2018-03-31 13F MERCK CS 58933Y105 1,374,252 199,999 17.03 66,458 0.58 1.5830
2018-02-07 2017-12-31 13F MERCK N CO INC CS 58933Y105 1,174,253 189,644 19.26 66,075 4.81 1.4525
2017-11-13 2017-09-30 13F MERCK N CO INC CS 58933Y105 984,609 6,128 0.63 63,044 0.53 1.4827
2017-08-07 2017-06-30 13F MERCK CS 58933Y105 978,481 -14,884 -1.50 62,712 -0.64 1.5383
2017-05-09 2017-03-31 13F MERCK AND CS 58933Y105 993,365 146,042 17.24 63,115 26.53 1.6241
2017-02-10 2016-12-31 13F MERCK and CS 58933Y105 847,323 79,513 10.36 49,881 4.09 1.3105
2016-11-07 2016-09-30 13F MERCK CS 58933Y105 767,810 -58,854 -7.12 47,919 0.62 1.2995
2016-08-12 2016-06-30 13F MERCK CS 58933Y105 826,664 42,162 5.37 47,625 14.74 1.2964
2016-05-11 2016-03-31 13F MERCK CS 58933Y105 784,502 34,539 4.61 41,508 4.78 1.1352
2016-02-12 2015-12-31 13F MERCK and CS 58933Y105 749,963 -66,058 -8.10 39,613 -2.61 1.1879
2015-10-30 2015-09-30 13F MERCK and CS 58933Y105 816,021 64,796 8.63 40,674 -4.90 1.2613
2015-08-12 2015-06-30 13F MERCK + COMPANY INC CS 58933Y105 751,225 -110,593 -12.83 42,768 -13.67 1.3004
2015-05-06 2015-03-31 13F MERCK CS 58933Y105 861,818 241,015 38.82 49,538 40.51 1.5153
2015-02-11 2014-12-31 13F MERCK CS 58933Y105 620,803 7,989 1.30 35,256 -2.95 1.0941
2014-11-20 2014-09-30 13F MERCK CS 58933Y105 612,814 -509 -0.08 36,327 2.39 1.2177
2014-08-19 2014-06-30 13F MERCK & CS 58933Y105 613,323 -576 -0.09 35,480 1.80 1.4609
2014-05-22 2014-03-31 13F MERCK & COMMON 58933Y105 613,899 -19,244 -3.04 34,851 9.98 1.5149
2014-05-22 2013-12-31 13F/A-1 MERCK & com 58933Y105 633,143 -53,283 -7.76 31,688 -3.04 1.4377
2014-02-24 2013-12-31 13F MERCK & com 58933Y105 633,143 31,688
2013-11-27 2013-09-30 13F MERCK COMMON 58933Y105 686,426 3,333 0.49 32,682 3.00 1.4683
2013-08-16 2013-06-30 13F MERCK COM 58933Y105 683,093 683,093 31,729 1.4870
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.