Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionCallahan Advisors, LLC
Latest Disclosed Ownership23,402 shares
Latest Disclosed Value $ 2,815,031
Callahan Advisors, LLC ownership in MRK / Merck & Co., Inc.

On May 12, 2026 - Callahan Advisors, LLC filed a 13F-HR form disclosing ownership of 23,402 shares of Merck & Co., Inc. (MX:MRK) valued at $2,815,031 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 6, 2026 disclosing 23,402 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)
2026-05-12 2026-03-31 13F Merck COM 58933Y105 23,402 0 0.00 2,815 14.29 0.2349
2026-02-06 2025-12-31 13F Merck COM 58933Y105 23,402 -515 -2.15 2,463 22.72 0.2025
2025-10-31 2025-09-30 13F Merck COM 58933Y105 23,917 -2,173 -8.33 2,007 -2.81 0.1705
2025-07-28 2025-06-30 13F Merck COM 58933Y105 26,090 -648 -2.42 2,065 -13.92 0.1856
2025-05-01 2025-03-31 13F Merck COM 58933Y105 26,738 -898 -3.25 2,400 -12.73 0.2287
2025-01-31 2024-12-31 13F Merck COM 58933Y105 27,636 -2,449 -8.14 2,749 -19.53 0.2587
2024-10-30 2024-09-30 13F Merck COM 58933Y105 30,085 -93 -0.31 3,416 -8.57 0.3329
2024-07-29 2024-06-30 13F Merck COM 58933Y105 30,178 -410 -1.34 3,736 -7.43 0.3885
2024-04-24 2024-03-31 13F Merck COM 58933Y105 30,588 7 0.02 4,036 21.09 0.4233
2024-01-24 2023-12-31 13F Merck COM 58933Y105 30,581 8 0.03 3,334 5.91 0.3868
2023-10-23 2023-09-30 13F Merck COM 58933Y105 30,573 1,577 5.44 3,148 -5.92 0.3953
2023-07-31 2023-06-30 13F Merck COM 58933Y105 28,996 -328 -1.12 3,346 7.25 0.4066
2023-04-28 2023-03-31 13F Merck COM 58933Y105 29,324 8 0.03 3,120 -4.09 0.4030
2023-02-03 2022-12-31 13F Merck COM 58933Y105 29,316 9 0.03 3,253 28.84 0.4451
2022-11-14 2022-09-30 13F/A-1 Merck COM 58933Y105 29,307 -2 -0.01 2,524 -5.54 0.3625
2022-10-27 2022-09-30 13F Merck COM 58933Y105 29,307 -2 2,524 0.3625
2022-07-29 2022-06-30 13F Merck COM 58933Y105 29,309 -11 -0.04 2,672 11.06 0.3557
2022-04-27 2022-03-31 13F Merck COM 58933Y105 29,320 3,872 15.22 2,406 23.38 0.2745
2022-02-08 2021-12-31 13F Merck COM 58933Y105 25,448 2,009 8.57 1,950 10.80 0.2188
2021-11-03 2021-09-30 13F Merck COM 58933Y105 23,439 17,931 325.54 1,760 311.21 0.2218
2021-08-11 2021-06-30 13F Merck COM 58933Y105 5,508 1,854 50.74 428 51.77 0.0543
2021-04-21 2021-03-31 13F Merck COM 58933Y105 3,654 9 0.25 282 -5.37 0.0382
2021-01-20 2020-12-31 13F Merck COM 58933Y105 3,645 -117 -3.11 298 -4.49 0.0436
2020-10-26 2020-09-30 13F Merck COM 58933Y105 3,762 309 8.95 312 16.85 0.0510
2020-07-17 2020-06-30 13F Merck COM 58933Y105 3,453 -189 -5.19 267 -4.64 0.0473
2020-04-06 2020-03-31 13F Merck COM 58933Y105 3,642 23 0.64 280 -14.89 0.0588
2020-01-21 2019-12-31 13F Merck COM 58933Y105 3,619 25 0.70 329 8.58 0.0527
2019-10-21 2019-09-30 13F Merck COM 58933Y105 3,594 7 0.20 303 0.66 0.0529
2019-07-17 2019-06-30 13F Merck COM 58933Y105 3,587 7 0.20 301 1.01 0.0540
2019-04-22 2019-03-31 13F Merck COM 58933Y105 3,580 842 30.75 298 42.58 0.0555
2019-01-24 2018-12-31 13F Merck COM 58933Y105 2,738 2,738 209 0.0446
2018-01-30 2017-12-31 13F Merck COM 58933Y105 0 -3,628 -100.00 0 -100.00
2017-10-26 2017-09-30 13F Merck COM 58933Y105 3,628 381 11.73 232 11.54 0.0488
2017-07-31 2017-06-30 13F Merck COM 58933Y105 3,247 3,247 208 0.0453
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.