Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionWestside Investment Management, Inc.
Latest Disclosed Ownership3,025 shares
Latest Disclosed Value $ 364,123
Westside Investment Management, Inc. reports 3.72% decrease in ownership of MRK / Merck & Co., Inc.

On May 4, 2026 - Westside Investment Management, Inc. filed a 13F-HR form disclosing ownership of 3,025 shares of Merck & Co., Inc. (MX:MRK) valued at $364,123 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 23, 2026 disclosing 3,142 shares of Merck & Co., Inc.. This represents a change in shares of -3.72% 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)
2026-05-04 2026-03-31 13F MERCK COM 58933Y105 3,025 -117 -3.72 364 9.97 0.0271
2026-01-23 2025-12-31 13F MERCK COM 58933Y105 3,142 93 3.05 331 28.29 0.0530
2025-11-04 2025-09-30 13F MERCK COM 58933Y105 3,049 305 11.12 258 18.89 0.0413
2025-08-05 2025-06-30 13F MERCK COM 58933Y105 2,744 -80 -2.83 218 -14.23 0.0403
2025-04-25 2025-03-31 13F MERCK COM 58933Y105 2,824 84 3.07 253 -6.99 0.0539
2025-01-17 2024-12-31 13F MERCK COM 58933Y105 2,740 -247 -8.27 273 -19.76 0.0575
2024-11-20 2024-09-30 13F MERCK COM 58933Y105 2,987 -46 -1.52 339 -9.60 0.0723
2024-07-17 2024-06-30 13F MERCK COM 58933Y105 3,033 21 0.70 376 -5.54 0.0860
2024-04-19 2024-03-31 13F MERCK COM 58933Y105 3,012 -185 -5.79 398 14.08 0.0953
2024-01-12 2023-12-31 13F MERCK COM 58933Y105 3,197 -48 -1.48 349 4.19 0.0891
2023-11-15 2023-09-30 13F MERCK COM 58933Y105 3,245 3 0.09 334 -10.70 0.0962
2023-07-14 2023-06-30 13F MERCK COM 58933Y105 3,242 -38 -1.16 374 7.16 0.1056
2023-05-17 2023-03-31 13F MERCK COM 58933Y105 3,280 2 0.06 349 6,880.00 0.1025
2023-01-31 2022-12-31 13F MERCK COM 58933Y105 3,278 3 0.09 6 25.00 0.0146
2022-11-09 2022-09-30 13F MERCK COM 58933Y105 3,275 252 8.34 5 0.00 0.0110
2022-07-15 2022-06-30 13F MERCK COM 58933Y105 3,023 -58 -1.88 4 0.00 0.0101
2022-04-25 2022-03-31 13F MERCK COM 58933Y105 3,081 -98 -3.08 4 0.00 0.0097
2022-02-15 2021-12-31 13F MERCK COM 58933Y105 3,179 192 6.43 4 0.00 0.0098
2021-10-27 2021-09-30 13F MERCK COM 58933Y105 2,987 49 1.67 4 0.00 0.0099
2021-07-28 2021-06-30 13F MERCK COM 58933Y105 2,938 189 6.88 4 0.00 0.0095
2021-04-14 2021-03-31 13F MERCK COM 58933Y105 2,749 -49 -1.75 4 0.0107
2021-01-15 2020-12-31 13F MERCK COM 58933Y105 2,798 62 2.27 0 0.0006
2020-10-14 2020-09-30 13F MERCK COM 58933Y105 2,736 2 0.07 0 0.0001
2020-07-21 2020-06-30 13F MERCK COM 58933Y105 2,734 1 0.04 0 0.48 0.0001
2020-04-16 2020-03-31 13F MERCK COM 58933Y105 2,733 -32 -1.16 0 -9.09 0.0001
2019-07-24 2019-06-30 13F MERCK COM 58933Y105 2,765 2 0.07 0 -100.00 0.0005
2019-02-05 2018-12-31 13F MERCK COM 58933Y105 2,763 -339 -10.93 211 -4.52 0.0773
2018-11-08 2018-09-30 13F MERCK COM 58933Y105 3,102 1 0.03 222 18.18 0.0709
2018-08-13 2018-06-30 13F MERCK COM 58933Y105 3,101 19 0.62 187 14.02 0.0660
2018-04-16 2018-03-31 13F MERCK COM 58933Y105 3,082 0 0.00 164 -5.75 0.0902
2018-02-15 2017-12-31 13F MERCK COM 58933Y105 3,082 184 6.35 175 -6.45 0.0946
2017-11-13 2017-09-30 13F MERCK COM 58933Y105 2,898 1 0.03 186 2.20 0.1125
2017-09-14 2017-06-30 13F/A-1 MERCK COM 58933Y105 2,897 189 6.98 182 5.81 0.1188
2017-08-15 2017-06-30 13F MERCK COM 58933Y105 2,897 189 182
2017-05-11 2017-03-31 13F MERCK COM 58933Y105 2,708 100 3.83 172 7.50 0.0822
2017-05-11 2016-12-31 13F MERCK COM 58933Y105 2,608 2,608 161 0.1094
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.