Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionGreat Valley Advisor Group, Inc.
Latest Disclosed Ownership45,768 shares
Latest Disclosed Value $ 5,505,928
Great Valley Advisor Group, Inc. reports 1.28% increase in ownership of MRK / Merck & Co., Inc.

On May 11, 2026 - Great Valley Advisor Group, Inc. filed a 13F-HR form disclosing ownership of 45,768 shares of Merck & Co., Inc. (MX:MRK) valued at $5,505,928 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 12, 2026 disclosing 45,189 shares of Merck & Co., Inc.. This represents a change in shares of 1.28% 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 45,768 579 1.28 5,506 15.75 0.1001
2026-02-12 2025-12-31 13F MERCK COM 58933Y105 45,189 -1,828 -3.89 4,757 20.53 0.0914
2025-11-14 2025-09-30 13F MERCK COM 58933Y105 47,017 -51,947 -52.49 3,947 -49.63 0.0791
2025-08-14 2025-06-30 13F MERCK COM 58933Y105 98,964 -5,160 -4.96 7,834 -16.17 0.1735
2025-05-08 2025-03-31 13F MERCK COM 58933Y105 104,124 -4,651 -4.28 9,346 -13.63 0.2012
2025-02-24 2024-12-31 13F MERCK COM 58933Y105 108,775 6,112 5.95 10,821 -7.19 0.2423
2024-11-12 2024-09-30 13F MERCK COM 58933Y105 102,663 7,064 7.39 11,658 -1.50 0.2865
2024-07-16 2024-06-30 13F MERCK COM 58933Y105 95,599 5,885 6.56 11,835 -0.02 0.3311
2024-05-06 2024-03-31 13F MERCK COM 58933Y105 89,714 -9,337 -9.43 11,838 9.62 0.3594
2024-02-06 2023-12-31 13F MERCK COM 58933Y105 99,051 5,982 6.43 10,799 12.70 0.3789
2023-11-07 2023-09-30 13F MERCK COM 58933Y105 93,069 9,052 10.77 9,581 -1.17 0.3972
2023-08-10 2023-06-30 13F MERCK COM 58933Y105 84,017 2,499 3.07 9,695 11.79 0.4063
2023-05-03 2023-03-31 13F MERCK COM 58933Y105 81,518 5,292 6.94 8,673 2.54 0.4044
2023-02-01 2022-12-31 13F MERCK COM 58933Y105 76,226 24,931 48.60 8,458 91.42 0.4322
2022-10-21 2022-09-30 13F MERCK COM 58933Y105 51,295 -1,372 -2.61 4,418 -8.00 0.2474
2022-07-19 2022-06-30 13F MERCK COM 58933Y105 52,667 6,745 14.69 4,802 32.07 0.2639
2022-04-20 2022-03-31 13F MERCK COM 58933Y105 45,922 -476 -1.03 3,636 3.30 0.2120
2022-02-10 2021-12-31 13F MERCK COM 58933Y105 46,398 -293 -0.63 3,520 0.37 0.2175
2021-10-14 2021-09-30 13F MERCK COM 58933Y105 46,691 -1,293 -2.69 3,507 -5.62 0.2417
2021-07-27 2021-06-30 13F MERCK COM 58933Y105 47,984 -313 -0.65 3,716 -0.19 0.2748
2021-04-20 2021-03-31 13F MERCK & CO. COM 58933Y105 48,297 -8,512 -14.98 3,723 -19.88 0.3583
2021-01-29 2020-12-31 13F MERCK & CO. COM 58933Y105 56,809 2,820 5.22 4,647 3.82 0.4808
2020-10-21 2020-09-30 13F MERCK & CO. COM 58933Y105 53,989 -1,423 -2.57 4,476 4.46 0.5494
2020-07-31 2020-06-30 13F MERCK & CO. COM 58933Y105 55,412 10,638 23.76 4,285 24.38 0.7013
2020-05-15 2020-03-31 13F MERCK & CO. COM 58933Y105 44,774 4,088 10.05 3,445 -6.92 0.9125
2020-02-10 2019-12-31 13F MERCK COM 58933Y105 40,686 -2,246 -5.23 3,701 2.58 0.8241
2019-10-25 2019-09-30 13F MERCK COM 58933Y105 42,932 492 1.16 3,608 1.52 0.8709
2019-07-30 2019-06-30 13F MERCK COM 58933Y105 42,440 18,070 74.15 3,554 75.42 0.8930
2019-04-26 2019-03-31 13F MERCK COM 58933Y105 24,370 6,186 34.02 2,026 45.86 0.6447
2019-04-11 2018-12-31 13F MERCK COM 58933Y105 18,184 18,184 1,389 0.5188
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.