Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionAmerican Investment Services, Inc.
Latest Disclosed Ownership66,477 shares
Latest Disclosed Value $ 7,996,519
American Investment Services, Inc. reports 19.13% increase in ownership of MRK / Merck & Co., Inc.

On May 13, 2026 - American Investment Services, Inc. filed a 13F-HR form disclosing ownership of 66,477 shares of Merck & Co., Inc. (MX:MRK) valued at $7,996,519 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 55,803 shares of Merck & Co., Inc.. This represents a change in shares of 19.13% 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)
2026-05-13 2026-03-31 13F MERCK COM 58933Y105 66,477 10,674 19.13 7,997 36.15 1.7837
2026-02-13 2025-12-31 13F MERCK COM 58933Y105 55,803 9,977 21.77 5,874 52.70 1.3632
2025-11-13 2025-09-30 13F MERCK COM 58933Y105 45,826 16,141 54.37 3,846 63.73 0.9241
2025-08-13 2025-06-30 13F MERCK COM 58933Y105 29,685 15,014 102.34 2,350 78.50 0.5998
2025-05-13 2025-03-31 13F MERCK COM 58933Y105 14,671 10,951 294.38 1,317 255.68 0.2318
2025-03-03 2024-12-31 13F/A-1 MERCK COM 58933Y105 3,720 1,430 62.45 370 42.31 0.0655
2025-02-14 2024-12-31 13F MERCK COM 58933Y105 2,290 0 260 0.0434
2024-11-14 2024-09-30 13F MERCK COM 58933Y105 2,290 0 0.00 260 -8.13 0.0434
2024-08-14 2024-06-30 13F MERCK COM 58933Y105 2,290 0 0.00 284 -6.29 0.0502
2024-05-13 2024-03-31 13F MERCK COM 58933Y105 2,290 2,290 302 0.0536
2020-08-03 2020-06-30 13F MERCK & CO. COM 58933Y105 0 -3,137 -100.00 0 -100.00
2020-04-28 2020-03-31 13F MERCK & CO. COM 58933Y105 3,137 199 6.77 241 -9.74 0.0924
2020-01-29 2019-12-31 13F MERCK COM 58933Y105 2,938 15 0.51 267 8.54 0.0807
2019-11-08 2019-09-30 13F MERCK COM 58933Y105 2,923 2,923 246 0.0772
2018-02-08 2017-12-31 13F MERCK COM 58933Y105 0 -3,172 -100.00 0 -100.00
2017-10-12 2017-09-30 13F MERCK COM 58933Y105 3,172 11 0.35 203 0.00 0.0777
2017-08-11 2017-06-30 13F MERCK COM 58933Y105 3,161 3,161 203 0.0805
2016-10-28 2016-09-30 13F MERCK COM 58933Y105 0 -3,898 -100.00 0 -100.00
2016-08-15 2016-06-30 13F/A-1 MERCK COM 58933Y105 3,898 -202 -4.93 225 3.69 0.0973
2016-07-12 2016-06-30 13F MERCK COM 58933Y105 3,898 -202 225 0.0973
2016-05-12 2016-03-31 13F MERCK & CO INC COM 58933Y105 4,100 4,100 0.00 217 0.1063
2016-02-10 2015-12-31 13F MERCK & CO INC COM 58933Y105 0 0 0 0.0000
2015-11-12 2015-09-30 13F MERCK & CO INC COM 58933Y105 0 -24,594 -100.00 0 -100.00
2015-07-08 2015-06-30 13F MERCK & CO INC COM 58933Y105 24,594 -37,005 -60.07 1,400 -60.46 0.7471
2015-04-17 2015-03-31 13F MERCK & CO INC COM 58933Y105 61,599 61,599 0.00 3,541 1.9215
2015-02-05 2014-12-31 13F MERCK & CO INC COM 58933Y105 0 -175,958 -100.00 0 -100.00
2014-10-21 2014-09-30 13F MERCK & CO INC COM 58933Y105 175,958 -65,942 -27.26 10,431 -25.46 5.7663
2014-07-22 2014-06-30 13F MERCK & CO INC COM 58933Y105 241,900 -21,089 -8.02 13,994 -6.27 7.6240
2014-04-24 2014-03-31 13F MERCK & CO INC COM 58933Y105 262,989 -61,949 -19.06 14,930 -8.20 8.5847
2014-01-08 2013-12-31 13F MERCK & CO INC COM 58933Y105 324,938 4,492 1.40 16,263 6.60 9.6966
2013-10-16 2013-09-30 13F MERCK & CO INC COM 58933Y105 320,446 370 0.12 15,256 2.61 9.5469
2013-08-06 2013-06-30 13F MERCK & CO INC COM 58933Y105 320,076 320,076 14,868 9.3250
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.