Merck & Co., Inc.
US ˙ NYSE ˙ US58933Y1055

SecurityMRK / Merck & Co., Inc.
InstitutionMairs & Power Inc
Latest Disclosed Ownership50,348 shares
Latest Disclosed Value $ 6,056,361
Mairs & Power Inc reports 3.18% decrease in ownership of MRK / Merck & Co., Inc.

On May 13, 2026 - Mairs & Power Inc filed a 13F-HR form disclosing ownership of 50,348 shares of Merck & Co., Inc. (US:MRK) valued at $6,056,361 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 51,999 shares of Merck & Co., Inc.. This represents a change in shares of -3.18% during the quarter. The current value of the position is $5,774,916 USD.

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)
2026-05-13 2026-03-31 13F MERCK COM 58933Y105 50,348 -1,651 -3.18 6,056 10.65 0.0619
2026-02-17 2025-12-31 13F MERCK COM 58933Y105 51,999 -188 -0.36 5,473 24.95 0.0527
2025-11-14 2025-09-30 13F MERCK COM 58933Y105 52,187 -4,684 -8.24 4,380 -2.69 0.0412
2025-08-14 2025-06-30 13F MERCK COM 58933Y105 56,871 3,712 6.98 4,502 -5.66 0.0444
2025-05-15 2025-03-31 13F MERCK COM 58933Y105 53,159 -741 -1.37 4,772 -11.01 0.0496
2025-02-14 2024-12-31 13F MERCK COM 58933Y105 53,900 513 0.96 5,362 -11.56 0.0519
2024-11-14 2024-09-30 13F MERCK COM 58933Y105 53,387 -1,464 -2.67 6,063 -10.72 0.0570
2024-08-14 2024-06-30 13F MERCK COM 58933Y105 54,851 -2,166 -3.80 6,791 -9.74 0.0656
2024-05-15 2024-03-31 13F MERCK COM 58933Y105 57,017 -4,967 -8.01 7,523 11.34 0.0728
2024-02-14 2023-12-31 13F MERCK COM 58933Y105 61,984 2,639 4.45 6,757 10.61 0.0712
2023-11-14 2023-09-30 13F MERCK COM 58933Y105 59,345 -388 -0.65 6,110 -11.36 0.0717
2023-08-14 2023-06-30 13F MERCK COM 58933Y105 59,733 -7,504 -11.16 6,893 -3.65 0.0750
2023-05-15 2023-03-31 13F MERCK COM 58933Y105 67,237 -6,229 -8.48 7,153 -12.24 0.0825
2023-02-14 2022-12-31 13F MERCK COM 58933Y105 73,466 -1,666 -2.22 8,151 25.98 0.0981
2022-11-14 2022-09-30 13F MERCK COM 58933Y105 75,132 18,289 32.17 6,470 24.86 0.0816
2022-08-15 2022-06-30 13F MERCK COM 58933Y105 56,843 -3,302 -5.49 5,182 5.01 0.0621
2022-05-16 2022-03-31 13F MERCK COM 58933Y105 60,145 -3,357 -5.29 4,935 1.40 0.0497
2022-02-14 2021-12-31 13F MERCK COM 58933Y105 63,502 -526 -0.82 4,867 1.21 0.0451
2021-11-15 2021-09-30 13F MERCK COM 58933Y105 64,028 -2,925 -4.37 4,809 -7.64 0.0481
2021-08-16 2021-06-30 13F MERCK COM 58933Y105 66,953 -8,920 -11.76 5,207 -10.98 0.0515
2021-05-14 2021-03-31 13F MERCK & CO. COM 58933Y105 75,873 -5,898 -7.21 5,849 -12.56 0.0614
2021-02-16 2020-12-31 13F MERCK & CO. COM 58933Y105 81,771 2,656 3.36 6,689 1.92 0.0743
2020-11-16 2020-09-30 13F MERCK & CO. COM 58933Y105 79,115 -1,715 -2.12 6,563 4.99 0.0820
2020-08-14 2020-06-30 13F MERCK & CO. COM 58933Y105 80,830 -824 -1.01 6,251 -0.49 0.0817
2020-05-15 2020-03-31 13F MERCK & CO. COM 58933Y105 81,654 -874 -1.06 6,282 -16.31 0.0917
2020-02-14 2019-12-31 13F Merck COM 58933Y105 82,528 2,063 2.56 7,506 10.81 0.0853
2019-11-14 2019-09-30 13F Merck COM 58933Y105 80,465 2,060 2.63 6,774 3.04 0.0819
2019-08-14 2019-06-30 13F Merck COM 58933Y105 78,405 -4,538 -5.47 6,574 -4.70 0.0789
2019-05-15 2019-03-31 13F Merck COM 58933Y105 82,943 -5,205 -5.90 6,898 2.42 0.0838
2019-02-14 2018-12-31 13F Merck COM 58933Y105 88,148 -1,085 -1.22 6,735 6.40 0.0909
2018-11-14 2018-09-30 13F Merck COM 58933Y105 89,233 -1,736 -1.91 6,330 14.63 0.0737
2018-08-14 2018-06-30 13F Merck COM 58933Y105 90,969 -2,352 -2.52 5,522 8.64 0.0685
2018-05-15 2018-03-31 13F Merck COM 58933Y105 93,321 7,929 9.29 5,083 5.79 0.0627
2018-02-14 2017-12-31 13F Merck COM 58933Y105 85,392 -2,811 -3.19 4,805 -14.93 0.0557
2017-11-14 2017-09-30 13F Merck COM 58933Y105 88,203 3,082 3.62 5,648 3.54 0.0678
2017-08-14 2017-06-30 13F Merck COM 58933Y105 85,121 -5,023 -5.57 5,455 -4.77 0.0659
2017-05-15 2017-03-31 13F Merck COM 58933Y105 90,144 -7,695 -7.86 5,728 -0.56 0.0702
2017-02-14 2016-12-31 13F Merck COM 58933Y105 97,839 906 0.93 5,760 -4.79 0.0740
2016-11-14 2016-09-30 13F Merck COM 58933Y105 96,933 -5,231 -5.12 6,050 2.79 0.0797
2016-08-15 2016-06-30 13F Merck COM 58933Y105 102,164 314 0.31 5,886 9.22 0.0795
2016-05-16 2016-03-31 13F Merck COM 58933Y105 101,850 -2,787 -2.66 5,389 -2.50 0.0766
2016-02-16 2015-12-31 13F Merck COM 58933Y105 104,637 513 0.49 5,527 7.47 0.0828
2015-11-16 2015-09-30 13F Merck COM 58933Y105 104,124 1,250 1.22 5,143 -12.19 0.0804
2015-08-14 2015-06-30 13F Merck COM 58933Y105 102,874 -2,284 -2.17 5,857 -3.09 0.0829
2015-05-15 2015-03-31 13F Merck COM 58933Y105 105,158 -2,526 -2.35 6,044 -1.16 0.0831
2015-02-17 2014-12-31 13F Merck COM 58933Y105 107,684 949 0.89 6,115 -3.35 0.0849
2014-11-14 2014-09-30 13F Merck COM 58933Y105 106,735 -811 -0.75 6,327 1.69 0.0923
2014-08-14 2014-06-30 13F Merck COM 58933Y105 107,546 -6,666 -5.84 6,222 -4.04 0.0882
2014-05-15 2014-03-31 13F Merck COM 58933Y105 114,212 -16,442 -12.58 6,484 -0.84 0.0961
2014-02-14 2013-12-31 13F Merck COM 58933Y105 130,654 17,250 15.21 6,539 21.12 0.1006
2013-11-14 2013-09-30 13F Merck COM 58933Y105 113,404 -22,884 -16.79 5,399 -14.72 0.0933
2013-08-14 2013-06-30 13F Merck COM 58933Y105 136,288 136,288 6,331 0.1210
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.