Merck & Co., Inc.
BG ˙ BUL ˙ US58933Y1055
SecurityBG:6MK / Merck & Co., Inc.
InstitutionState Street Corp
Latest Disclosed Ownership119,325,673 shares
Latest Disclosed Value $ 14,453,274,004
State Street Corp reports 0.60% decrease in ownership of 6MK / Merck & Co., Inc.

On May 15, 2026 - State Street Corp filed a 13F-HR form disclosing ownership of 119,325,673 shares of Merck & Co., Inc. (BG:6MK) valued at $14,453,274,004 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 120,040,168 shares of Merck & Co., Inc.. This represents a change in shares of -0.60% 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)
2026-05-15 2026-03-31 13F MERCK COM 58933Y105 119,325,673 -714,495 -0.60 14,453,274 13.47 0.4990
2026-02-13 2025-12-31 13F MERCK COM 58933Y105 120,040,168 1,859,990 1.57 12,737,504 27.20 0.4273
2025-11-14 2025-09-30 13F MERCK COM 58933Y105 118,180,178 -313,686 -0.26 10,013,630 5.70 0.3472
2025-08-14 2025-06-30 13F MERCK COM 58933Y105 118,493,864 -2,035,776 -1.69 9,473,928 -13.20 0.3551
2025-05-15 2025-03-31 13F MERCK COM 58933Y105 120,529,640 -379,666 -0.31 10,914,833 -9.97 0.4498
2025-02-14 2024-12-31 13F MERCK COM 58933Y105 120,909,306 1,882,894 1.58 12,123,449 -10.90 0.4783
2024-11-14 2024-09-30 13F MERCK COM 58933Y105 119,026,412 1,536,474 1.31 13,606,360 -7.01 0.5536
2024-08-14 2024-06-30 13F MERCK COM 58933Y105 117,489,938 64,408 0.05 14,632,538 -6.10 0.6394
2024-05-15 2024-03-31 13F MERCK COM 58933Y105 117,425,530 559,553 0.48 15,583,895 21.48 0.6966
2024-02-14 2023-12-31 13F MERCK COM 58933Y105 116,865,977 1,196,373 1.03 12,828,427 6.98 0.6240
2023-11-14 2023-09-30 13F MERCK COM 58933Y105 115,669,604 -2,892,482 -2.44 11,991,917 -12.89 0.6649
2023-08-14 2023-06-30 13F MERCK COM 58933Y105 118,562,086 2,174,829 1.87 13,766,428 10.43 0.7230
2023-05-15 2023-03-31 13F MERCK COM 58933Y105 116,387,257 -1,574,600 -1.33 12,466,090 -5.36 0.7035
2023-05-15 2022-12-31 13F/A-99 MERCK COM 58933Y105 117,961,857 650,528 0.55 13,171,751 29.36 0.7739
2023-05-15 2022-12-31 13F MERCK COM 58933Y105 117,961,857 650,528 13,171,751 0.7739
2022-11-15 2022-09-30 13F MERCK COM 58933Y105 117,311,329 -480,300 -0.41 10,182,187 -5.89 0.6440
2022-08-15 2022-06-30 13F MERCK COM 58933Y105 117,791,629 -530,761 -0.45 10,819,008 10.53 0.6483
2022-05-16 2022-03-31 13F MERCK COM 58933Y105 118,322,390 -346,283 -0.29 9,788,280 6.69 0.4840
2022-02-14 2021-12-31 13F MERCK COM 58933Y105 118,668,673 3,132,078 2.71 9,174,491 4.82 0.4351
2021-11-15 2021-09-30 13F MERCK COM 58933Y105 115,536,595 1,462,650 1.28 8,752,949 -2.13 0.4626
2021-08-16 2021-06-30 13F MERCK COM 58933Y105 114,073,945 1,385,011 1.23 8,943,537 2.11 0.4714
2021-07-09 2021-03-31 13F/A-1 MERCK & CO. COM 58933Y105 112,688,934 -1,463,511 -1.28 8,759,110 -6.94 0.5022
2021-05-17 2021-03-31 13F MERCK & CO. COM 58933Y105 112,688,934 -1,463,511 8,759,110 0.5023
2021-02-16 2020-12-31 13F MERCK & CO. COM 58933Y105 114,152,445 -2,877,669 -2.46 9,411,944 -3.75 0.5763
2020-11-10 2020-09-30 13F MERCK & CO. COM 58933Y105 117,030,114 -1,761,018 -1.48 9,778,775 5.62 0.6676
2020-08-14 2020-06-30 13F MERCK & CO. COM 58933Y105 118,791,132 1,447,774 1.23 9,258,270 1.76 0.6731
2020-06-19 2020-03-31 13F/A-1 MERCK & CO. COM 58933Y105 117,343,358 849,474 0.73 9,098,570 -14.69 0.7957
2020-05-11 2020-03-31 13F MERCK & CO. COM 58933Y105 117,343,358 849,474 9,098,570 799,037.6480
2020-02-06 2019-12-31 13F MERCK COM 58933Y105 116,493,884 1,196,724 1.04 10,665,449 9.18 0.7305
2019-11-14 2019-09-30 13F MERCK COM 58933Y105 115,297,160 -1,226,956 -1.05 9,768,882 -0.66 0.7281
2019-08-14 2019-06-30 13F MERCK COM 58933Y105 116,524,116 -677,982 -0.58 9,833,920 0.23 0.7332
2019-05-15 2019-03-31 13F MERCK COM 58933Y105 117,202,098 5,528,468 4.95 9,811,648 14.16 0.7655
2019-02-12 2018-12-31 13F MERCK COM 58933Y105 111,673,630 -1,182,759 -1.05 8,594,307 7.35 0.7825
2018-11-09 2018-09-30 13F MERCK Common equity shares 58933Y105 112,856,389 3,456,351 3.16 8,006,184 20.56 0.6149
2018-08-14 2018-06-30 13F MERCK ; Common equity shares 58933Y105 109,400,038 -2,730,943 -2.44 6,640,735 8.73 0.5551
2018-05-15 2018-03-31 13F MERCK Common equity shares 58933Y105 112,130,981 -6,257,686 -5.29 6,107,771 -8.32 0.5186
2018-02-14 2017-12-31 13F MERCK ; Common equity shares 58933Y105 118,388,667 568,111 0.48 6,661,870 -11.70 0.5357
2017-11-14 2017-09-30 13F MERCK &; Common equity shares 58933Y105 117,820,556 -2,874,394 -2.38 7,544,188 -2.47 0.6509
2017-08-14 2017-06-30 13F MERCK Common equity shares 58933Y105 120,694,950 -2,372,655 -1.93 7,735,487 -1.08 0.6842
2017-05-15 2017-03-31 13F MERCK Common equity shares 58933Y105 123,067,605 -2,078,725 -1.66 7,820,092 6.11 0.6976
2017-02-09 2016-12-31 13F MERCK Common equity shares 58933Y105 125,146,330 3,715,771 3.06 7,369,619 -2.79 0.6935
2017-01-13 2016-09-30 13F/A-1 MERCK Common equity shares 58933Y105 121,430,559 7,135,749 6.24 7,581,026 15.13 0.7641
2016-11-14 2016-09-30 13F MERCK Common equity shares 58933Y105 86,801,544 5,419,829
2016-08-12 2016-06-30 13F MERCK Common equity shares 58933Y105 114,294,810 -1,749,922 -1.51 6,584,537 7.24 0.7073
2016-05-20 2016-03-31 13F/A-1 MERCK & Common equity shares 58933Y105 116,044,732 -3,274,566 -2.74 6,139,924 -2.58 0.6638
2016-05-12 2016-03-31 13F MERCK & Common equity shares 58933Y105 116,044,732 6,139,924
2016-02-16 2015-12-31 13F MERCK Common equity shares 58933Y105 119,319,298 1,546,828 1.31 6,302,443 8.35 0.6888
2015-11-16 2015-09-30 13F MERCK Common equity shares 58933Y105 117,772,470 -1,666,530 -1.40 5,816,779 -14.46 0.6771
2015-08-13 2015-06-30 13F MERCK & Common equity shares 58933Y105 119,439,000 -4,499,871 -3.63 6,799,734 -4.55 0.7268
2015-05-15 2015-03-31 13F MERCK Common equity shares 58933Y105 123,938,871 -4,063,797 -3.17 7,123,994 -2.00 0.7311
2015-02-11 2014-12-31 13F MERCK Common equity shares 58933Y105 128,002,668 1,860,548 1.47 7,269,274 -2.79 0.7240
2014-11-12 2014-09-30 13F/A-1 MERCK Common equity shares 58933Y105 126,142,120 1,818,482 1.46 7,477,707 3.97 0.8046
2014-11-10 2014-09-30 13F MERCK Common equity shares 58933Y105 126,142,120 7,477,707
2014-08-12 2014-06-30 13F MERCK Common equity shares 58933Y105 124,323,638 -4,069,934 -3.17 7,192,124 -1.33 0.7767
2014-05-15 2014-03-31 13F/A-1 MERCK Common equity shares 58933Y105 128,393,572 -3,707,723 -2.81 7,288,900 10.24 0.8283
2014-05-13 2014-03-31 13F MERCK Common equity shares 58933Y105 128,393,572 7,288,900
2014-02-06 2013-12-31 13F/A-1 MERCK Common equity shares 58933Y105 132,101,295 2,182,322 1.68 6,611,665 6.89 0.7355
2014-02-06 2013-12-31 13F MERCK Common equity shares 58933Y105 131,523,514 5,384,571
2013-11-12 2013-09-30 13F MERCK Common equity shares 58933Y105 129,918,973 -242,566 -0.19 6,185,436 2.31 0.7622
2013-08-08 2013-06-30 13F MERCK Common equity shares 58933Y105 130,161,539 130,161,539 6,045,999 0.7882
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.