Merck & Co., Inc.
BG ˙ BUL ˙ US58933Y1055
SecurityBG:6MK / Merck & Co., Inc.
InstitutionOsterweis Capital Management Inc
Latest Disclosed Ownership4,183 shares
Latest Disclosed Value $ 503,173
Osterweis Capital Management Inc reports 5.60% decrease in ownership of 6MK / Merck & Co., Inc.

On May 15, 2026 - Osterweis Capital Management Inc filed a 13F-HR form disclosing ownership of 4,183 shares of Merck & Co., Inc. (BG:6MK) valued at $503,173 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 4,431 shares of Merck & Co., Inc.. This represents a change in shares of -5.60% 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)
2026-05-15 2026-03-31 13F MERCK COM 58933Y105 4,183 -248 -5.60 503 7.94 0.0197
2026-02-17 2025-12-31 13F MERCK COM 58933Y105 4,431 248 5.93 466 32.76 0.0197
2025-11-14 2025-09-30 13F MERCK COM 58933Y105 4,183 -498 -10.64 351 -5.14 0.0158
2025-08-14 2025-06-30 13F MERCK COM 58933Y105 4,681 463 10.98 371 -2.12 0.0177
2025-06-05 2025-03-31 13F/A-1 MERCK COM 58933Y105 4,218 35 0.84 379 -9.13 0.0187
2025-05-14 2025-03-31 13F MERCK COM 58933Y105 4,218 35 3,786 0.0150
2025-06-05 2024-12-31 13F/A-1 MERCK COM 58933Y105 4,183 0 0.00 416 -12.42 0.0194
2025-02-13 2024-12-31 13F MERCK COM 58933Y105 4,183 0 0 0.0194
2024-11-14 2024-09-30 13F MERCK COM 58933Y105 4,183 -620 -12.91 475 -20.03 0.0241
2024-08-14 2024-06-30 13F MERCK COM 58933Y105 4,803 0 0.00 595 -6.16 0.0307
2024-05-15 2024-03-31 13F MERCK COM 58933Y105 4,803 -749 -13.49 634 4.63 0.0372
2024-02-14 2023-12-31 13F MERCK COM 58933Y105 5,552 -95 -1.68 605 4.13 0.0384
2023-11-14 2023-09-30 13F MERCK COM 58933Y105 5,647 0 0.00 581 -10.75 0.0426
2023-08-14 2023-06-30 13F MERCK COM 58933Y105 5,647 -85 -1.48 652 6.90 0.0431
2023-05-15 2023-03-31 13F MERCK COM 58933Y105 5,732 0 0.00 610 -4.09 0.0415
2023-02-14 2022-12-31 13F MERCK COM 58933Y105 5,732 654 12.88 636 45.31 0.0462
2022-11-14 2022-09-30 13F MERCK COM 58933Y105 5,078 0 0.00 437 -5.62 0.0328
2022-08-15 2022-06-30 13F MERCK COM 58933Y105 5,078 428 9.20 463 21.20 0.0347
2022-05-16 2022-03-31 13F MERCK COM 58933Y105 4,650 -428 -8.43 382 -1.80 0.0210
2022-02-14 2021-12-31 13F MERCK COM 58933Y105 5,078 428 9.20 389 11.46 0.0195
2021-11-15 2021-09-30 13F MERCK COM 58933Y105 4,650 -558 -10.71 349 -13.83 0.0191
2021-08-16 2021-06-30 13F MERCK COM 58933Y105 5,208 0 0.00 405 1.00 0.0208
2021-05-14 2021-03-31 13F MERCK & CO. COM 58933Y105 5,208 -461 -8.13 401 -13.58 0.0219
2021-02-12 2020-12-31 13F MERCK & CO. COM 58933Y105 5,669 735 14.90 464 13.45 0.0277
2020-11-13 2020-09-30 13F MERCK & CO. COM 58933Y105 4,934 -6,975 -58.57 409 -55.59 0.0276
2020-08-14 2020-06-30 13F MERCK & CO. COM 58933Y105 11,909 -60 -0.50 921 0.00 0.0668
2020-05-15 2020-03-31 13F MERCK & CO. COM 58933Y105 11,969 -265 -2.17 921 -17.18 0.0748
2020-02-14 2019-12-31 13F MERCK COM 58933Y105 12,234 0 0.00 1,112 7.96 0.0769
2019-11-14 2019-09-30 13F MERCK COM 58933Y105 12,234 456 3.87 1,030 4.25 0.0751
2019-08-14 2019-06-30 13F MERCK COM 58933Y105 11,778 0 0.00 988 0.92 0.0698
2019-05-15 2019-03-31 13F MERCK COM 58933Y105 11,778 783 7.12 979 16.55 0.0613
2019-02-13 2018-12-31 13F MERCK COM 58933Y105 10,995 -783 -6.65 840 0.48 0.0646
2018-11-13 2018-09-30 13F MERCK COM 58933Y105 11,778 265 2.30 836 19.60 0.0534
2018-08-13 2018-06-30 13F MERCK COM 58933Y105 11,513 0 0.00 699 11.31 0.0452
2018-05-14 2018-03-31 13F MERCK COM 58933Y105 11,513 0 0.00 628 -2.94 0.0447
2018-02-14 2017-12-31 13F MERCK COM 58933Y105 11,513 -243 -2.07 647 -13.96 0.0459
2017-11-13 2017-09-30 13F MERCK COM 58933Y105 11,756 0 0.00 752 -0.27 0.0564
2017-08-15 2017-06-30 13F MERCK COM 58933Y105 11,756 0 0.00 754 0.80 0.0574
2017-05-12 2017-03-31 13F MERCK COM 58933Y105 11,756 0 0.00 748 8.09 0.0585
2017-02-13 2016-12-31 13F MERCK COM 58933Y105 11,756 -365 -3.01 692 -8.47 0.0499
2016-11-14 2016-09-30 13F MERCK COM 58933Y105 12,121 0 0.00 756 8.31 0.0455
2016-08-12 2016-06-30 13F MERCK COM 58933Y105 12,121 783 6.91 698 16.33 0.0445
2016-05-16 2016-03-31 13F MERCK & CO INC COM 58933Y105 11,338 0 0.00 600 0.17 0.0349
2016-02-11 2015-12-31 13F MERCK & CO INC COM 58933Y105 11,338 -783 -6.46 599 0.17 0.0552
2015-11-13 2015-09-30 13F MERCK & CO INC COM 58933Y105 12,121 0 0.00 598 -13.46 0.0271
2015-08-17 2015-06-30 13F MERCK & CO INC COM 58933Y105 12,121 0 0.00 691 -0.86 0.0241
2015-05-14 2015-03-31 13F MERCK & CO INC COM 58933Y105 12,121 0 0.00 697 1.31 0.0223
2015-02-13 2014-12-31 13F MERCK & CO INC COM 58933Y105 12,121 0 0.00 688 -4.18 0.0226
2014-11-13 2014-09-30 13F MERCK & CO INC COM 58933Y105 12,121 0 0.00 718 2.43 0.0221
2014-08-14 2014-06-30 13F MERCK & CO INC COM 58933Y105 12,121 -516 -4.08 701 -2.23 0.0201
2014-05-15 2014-03-31 13F MERCK & CO INC COM 58933Y105 12,637 0 0.00 717 13.45 0.0220
2014-02-13 2013-12-31 13F MERCK & CO INC COM 58933Y105 12,637 783 6.61 632 18.35 0.0196
2013-11-14 2013-09-30 13F MERCK & CO INC COM 58933Y105 11,854 -783 -6.20 534 -8.87 0.0172
2013-08-15 2013-06-30 13F MERCK & CO INC COM 58933Y105 12,637 12,637 586 0.0219
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.