Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionBarton Investment Management
Latest Disclosed Ownership8,158 shares
Latest Disclosed Value $ 981,326
Barton Investment Management ownership in MRK / Merck & Co., Inc.

On April 20, 2026 - Barton Investment Management filed a 13F-HR form disclosing ownership of 8,158 shares of Merck & Co., Inc. (MX:MRK) valued at $981,326 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 21, 2026 disclosing 8,158 shares of Merck & Co., Inc.. This represents a change in shares of 0.00% 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)
2026-04-20 2026-03-31 13F MERCK COM 58933Y105 8,158 0 0.00 981 14.34 0.1231
2026-01-21 2025-12-31 13F MERCK COM 58933Y105 8,158 0 0.00 859 25.44 0.0925
2025-10-21 2025-09-30 13F MERCK COM 58933Y105 8,158 0 0.00 685 6.05 0.0697
2025-07-21 2025-06-30 13F MERCK COM 58933Y105 8,158 0 0.00 646 -11.89 0.0669
2025-04-11 2025-03-31 13F MERCK COM 58933Y105 8,158 0 0.00 732 -9.74 0.0900
2025-01-27 2024-12-31 13F MERCK COM 58933Y105 8,158 0 0.00 812 -12.42 0.0861
2024-10-17 2024-09-30 13F MERCK COM 58933Y105 8,158 0 0.00 926 -8.23 0.1158
2024-07-18 2024-06-30 13F MERCK COM 58933Y105 8,158 0 0.00 1,010 -6.23 0.1344
2024-04-26 2024-03-31 13F MERCK COM 58933Y105 8,158 0 0.00 1,076 21.03 0.1306
2024-01-24 2023-12-31 13F/A-1 MERCK COM 58933Y105 8,158 0 0.00 889 5.96 0.1166
2024-01-23 2023-12-31 13F MERCK COM 58933Y105 8,158 0 840 0.1356
2023-10-16 2023-09-30 13F MERCK COM 58933Y105 8,158 0 0.00 840 -10.84 0.1356
2023-07-24 2023-06-30 13F MERCK COM 58933Y105 8,158 0 0.00 941 8.54 0.1414
2023-04-18 2023-03-31 13F MERCK COM 58933Y105 8,158 0 0.00 868 -4.20 0.1527
2023-01-26 2022-12-31 13F MERCK COM 58933Y105 8,158 0 0.00 905 28.73 0.1779
2022-10-20 2022-09-30 13F Merck COM 58933Y105 8,158 0 0.00 703 -5.51 0.1430
2022-07-15 2022-06-30 13F Merck COM 58933Y105 8,158 0 0.00 744 11.21 0.1504
2022-04-20 2022-03-31 13F Merck COM 58933Y105 8,158 0 0.00 669 7.04 0.0847
2022-01-18 2021-12-31 13F Merck COM 58933Y105 8,158 -176 -2.11 625 -0.16 0.0543
2021-10-18 2021-09-30 13F Merck COM 58933Y105 8,334 0 0.00 626 -3.40 0.0524
2021-07-26 2021-06-30 13F Merck COM 58933Y105 8,334 0 0.00 648 0.93 0.0532
2021-04-16 2021-03-31 13F Merck COM 58933Y105 8,334 0 0.00 642 -5.87 0.0598
2021-01-13 2020-12-31 13F Merck COM 58933Y105 8,334 0 0.00 682 -1.30 0.0585
2020-10-19 2020-09-30 13F Merck COM 58933Y105 8,334 -2,238 -21.17 691 -15.53 0.0664
2020-08-17 2020-06-30 13F Merck COM 58933Y105 10,572 0 0.00 818 0.62 0.0832
2020-04-30 2020-03-31 13F Merck COM 58933Y105 10,572 0 0.00 813 -15.49 0.1260
2020-01-22 2019-12-31 13F Merck COM 58933Y105 10,572 0 0.00 962 8.09 0.1494
2019-10-16 2019-09-30 13F Merck COM 58933Y105 10,572 0 0.00 890 0.45 0.1492
2019-07-18 2019-06-30 13F Merck COM 58933Y105 10,572 -88 -0.83 886 -0.11 0.1324
2019-04-24 2019-03-31 13F Merck COM 58933Y105 10,660 0 0.00 887 8.83 0.1480
2019-01-22 2018-12-31 13F/A-1 Merck COM 58933Y105 10,660 0 0.00 815 7.80 0.1628
2019-01-16 2018-12-31 13F Merck COM 58933Y105 10,660 0 815
2018-10-23 2018-09-30 13F Merck COM 58933Y105 10,660 0 0.00 756 16.85 0.1170
2018-07-18 2018-06-30 13F Merck COM 58933Y105 10,660 0 0.00 647 11.36 0.1047
2018-04-18 2018-03-31 13F/A-1 Merck Equities 58933Y105 10,660 -88 -0.82 581 -3.97 0.1071
2018-01-18 2017-12-31 13F Merck COM 58933Y105 10,748 0 0.00 605 -12.06 0.1328
2017-10-30 2017-09-30 13F Merck COM 58933Y105 10,748 -176 -1.61 688 -1.71 0.1631
2017-07-25 2017-06-30 13F Merck COM 58933Y105 10,924 0 0.00 700 0.86 0.1847
2017-04-26 2017-03-31 13F Merck COM 58933Y105 10,924 -1,500 -12.07 694 -5.06 0.2018
2017-01-24 2016-12-31 13F Merck COM 58933Y105 12,424 0 0.00 731 -5.68 0.2431
2016-11-08 2016-09-30 13F Merck Com 58933Y105 12,424 0 0.00 775 8.39 0.2609
2016-08-03 2016-06-30 13F Merck Equities 58933Y105 12,424 -19,281 -60.81 715 -57.36 0.2602
2016-04-28 2016-03-31 13F Merck COM 58933Y105 31,705 19,281 155.19 1,677 155.64 0.4600
2016-02-08 2015-12-31 13F Merck COM 58933Y105 12,424 0 0.00 656 7.01 0.2152
2015-11-06 2015-09-30 13F Merck COM 58933Y105 12,424 0 0.00 613 -13.30 0.2227
2015-08-18 2015-06-30 13F Merck COM 58933Y105 12,424 0 0.00 707 -0.98 0.2502
2015-05-07 2015-03-31 13F Merck COM 58933Y105 12,424 -150 -1.19 714 0.00 0.2631
2015-02-06 2014-12-31 13F Merck COM 58933Y105 12,574 0 0.00 714 -4.16 0.2734
2014-11-14 2014-09-30 13F Merck COM 58933Y105 12,574 528 4.38 745 6.89 0.2850
2014-08-11 2014-06-30 13F Merck COM 58933Y105 12,046 0 0.00 697 1.90 0.2725
2014-05-08 2014-03-31 13F Merck COM 58933Y105 12,046 -1,000 -7.67 684 4.75 0.2798
2014-02-11 2013-12-31 13F Merck COM 58933Y105 13,046 0 0.00 653 5.15 0.2615
2013-11-07 2013-09-30 13F Merck COM 58933Y105 13,046 0 0.00 621 2.48 0.2808
2013-08-09 2013-06-30 13F Merck COM 58933Y105 13,046 13,046 606 0.3134
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.