Merck & Co., Inc.
US ˙ NYSE ˙ US58933Y1055

SecurityMRK / Merck & Co., Inc.
InstitutionNatixis
Latest Disclosed Ownership510,056 shares
Latest Disclosed Value $ 61,354,636
Natixis ownership in MRK / Merck & Co., Inc.

On May 14, 2026 - Natixis filed a 13F-HR form disclosing ownership of 510,056 shares of Merck & Co., Inc. (US:MRK) valued at $61,354,636 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 308,772 shares of Merck & Co., Inc.. This represents a change in shares of 65.19% during the quarter. The current value of the position is $58,503,423 USD.

Natixis has a history of taking positions in derivatives of the underlying security (MRK) in the form of stock options. The firm currently holds call options representing 0 of underlying shares valued at $0 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

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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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

MRK / Merck & Co., Inc. Historical Put/Call Ratio
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)
2026-05-14 2026-03-31 13F MERCK COM 58933Y105 510,056 201,284 65.19 61,355 88.78 0.1985
2026-02-13 2025-12-31 13F MERCK COM 58933Y105 308,772 -560,550 -64.48 32,501 -55.45 0.1154
2025-11-14 2025-09-30 13F MERCK COM 58933Y105 869,322 268,394 44.66 72,962 53.38 0.3383
2025-08-13 2025-06-30 13F MERCK COM 58933Y105 600,928 -852,150 -58.64 47,569 -63.32 0.2109
2025-07-18 2025-03-31 13F/A-1 MERCK COM 58933Y105 1,453,078 1,103,453 315.61 129,687 272.88 0.7061
2025-05-14 2025-03-31 13F MERCK COM 58933Y105 1,453,078 1,103,453 129,687 0.7113
2025-02-13 2024-12-31 13F MERCK COM 58933Y105 349,625 32,845 10.37 34,781 -3.32 0.2125
2024-11-13 2024-09-30 13F MERCK COM 58933Y105 316,780 -78,745 -19.91 35,974 -26.53 0.2028
2024-08-13 2024-06-30 13F MERCK COM 58933Y105 395,525 -904,577 -69.58 48,966 -71.46 0.2803
2024-05-13 2024-03-31 13F MERCK COM 58933Y105 1,300,102 -617,897 -32.22 171,548 -17.96 0.8918
2024-02-13 2023-12-31 13F MERCK COM 58933Y105 1,917,999 1,034,806 117.17 209,100 129.97 1.5189
2023-11-14 2023-09-30 13F MERCK COM 58933Y105 883,193 392,860 80.12 90,925 60.70 0.6959
2023-08-11 2023-06-30 13F MERCK COM 58933Y105 490,333 -188,794 -27.80 56,580 -21.69 0.4595
2023-05-12 2023-03-31 13F MERCK COM 58933Y105 679,127 -291,077 -30.00 72,252 -32.88 0.6517
2023-02-24 2022-12-31 13F/A-1 MERCK COM 58933Y105 970,204 -2,216,448 -69.55 107,645 -60.86 0.6039
2023-02-13 2022-12-31 13F MERCK COM 58933Y105 914,199 -2,272,453 101,130 0.0002
2022-11-14 2022-09-30 13F Merck COM 58933Y105 3,186,652 2,815,455 758.48 275,057 712.10 1.2874
2022-08-12 2022-06-30 13F Merck COM 58933Y105 371,197 -1,824,790 -83.10 33,870 -81.20 0.1228
2022-05-13 2022-03-31 13F MERCK COM 58933Y105 2,195,987 1,564,187 247.58 180,181 272.11 0.6278
2022-02-14 2021-12-31 13F MERCK COM 58933Y105 631,800 -1,309,825 -67.46 48,421 -66.80 0.1653
2021-11-12 2021-09-30 13F MERCK COM 58933Y105 1,941,625 -268,753 -12.16 145,835 -15.16 0.5040
2021-08-13 2021-06-30 13F MERCK COM 58933Y105 2,210,378 589,914 36.40 171,901 37.61 0.7508
2021-05-14 2021-03-31 13F MERCK & CO. CO 58933Y105 1,620,464 -737,857 -31.29 124,922 -35.24 0.4086
2021-02-12 2020-12-31 13F MERCK & CO. COM 58933Y105 2,358,321 1,547,137 190.73 192,910 186.69 0.7008
2020-11-12 2020-09-30 13F MERCK & CO. COM 58933Y105 811,184 705,015 664.05 67,288 719.59 0.4954
2020-08-13 2020-06-30 13F MERCK & CO. COM 58933Y105 106,169 -2,281,207 -95.55 8,210 -95.46 0.0638
2020-05-14 2020-03-31 13F MERCK & CO. COM 58933Y105 2,387,376 1,814,627 316.83 180,666 246.52 1.4196
2020-02-14 2019-12-31 13F MERCK COM 58933Y105 572,749 -558,099 -49.35 52,137 -45.23 0.3230
2019-11-13 2019-09-30 13F MERCK COM 58933Y105 1,130,848 -756,753 -40.09 95,195 -39.85 0.6130
2019-08-13 2019-06-30 13F MERCK COM 58933Y105 1,887,601 1,887,601 158,275 1.2514
2019-02-14 2018-12-31 13F/A-1 MERCK COM 58933Y105 0 -2,340,208 -100.00 0 -100.00
2018-11-14 2018-09-30 13F MERCK COM 58933Y105 2,340,208 954,271 68.85 166,013 97.34 0.9599
2018-08-14 2018-06-30 13F MERCK COM 58933Y105 1,385,937 -1,654,921 -54.42 84,127 -49.21 0.4454
2018-05-15 2018-03-31 13F MERCK COM 58933Y105 3,040,858 2,287,728 303.76 165,636 290.85 1.0169
2018-02-14 2017-12-31 13F MERCK COM 58933Y105 753,130 23,370 3.20 42,378 -9.31 0.3258
2017-11-14 2017-09-30 13F MERCK COM 58933Y105 729,760 729,760 46,726 0.4307
2017-08-14 2017-06-30 13F MERCK COM 58933Y105 0 -862,800 -100.00 0 -100.00
2017-05-15 2017-03-31 13F MERCK COM 58933Y105 862,800 559,878 184.83 54,813 207.37 0.6831
2017-02-14 2016-12-31 13F MERCK COM 58933Y105 302,922 -862,615 -74.01 17,833 -75.48 0.1837
2016-11-14 2016-09-30 13F MERCK COM 58933Y105 1,165,537 1,160,314 22,215.47 72,741 24,066.45 0.8406
2016-08-15 2016-06-30 13F MERCK COM 58933Y105 5,223 5,223 0.00 301 0.0056
2016-05-16 2016-03-31 13F MERCK & CO INC COM 58933Y105 0 -218,716 -100.00 0 -100.00
2016-02-16 2015-12-31 13F MERCK & CO INC NEW COM COM 58933Y105 218,716 -870,447 -79.92 11,554 -78.52 0.1924
2015-11-16 2015-09-30 13F MERCK & CO INC COM 58933Y105 1,089,163 -42,514 -3.76 53,793 -16.50 1.1239
2015-08-14 2015-06-30 13F MERCK & CO INC COM 58933Y105 1,131,677 568,965 101.11 64,426 99.18 0.8714
2015-05-22 2015-03-31 13F MERCK & CO INC COM 58933Y105 562,712 390,704 227.14 32,345 231.06 0.4445
2015-02-17 2014-12-31 13F MERCK & CO INC COM 58933Y105 172,008 -88,059 -33.86 9,770 -36.63 0.1349
2014-11-14 2014-09-30 13F MERCK & CO INC COM 58933Y105 260,067 -904,225 -77.66 15,417 -77.11 0.2377
2014-08-14 2014-06-30 13F MERCK & CO INC COM 58933Y105 1,164,292 396,971 51.73 67,355 54.63 0.8095
2014-05-14 2014-03-31 13F MERCK & CO INC COM 58933Y105 767,321 466,750 155.29 43,558 189.56 0.5668
2014-02-14 2013-12-31 13F MERCK & CO INC COM 58933Y105 300,571 -95,135 -24.04 15,043 -20.15 0.1291
2013-11-14 2013-09-30 13F MERCK & CO INC COM 58933Y105 395,706 387,672 4,825.39 18,838 4,936.90 0.2012
2013-08-14 2013-06-30 13F MERCK & CO INC COM 58933Y105 8,034 8,034 374 0.0053
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2023-05-12 2023-03-31 13F Merck CALL Call 0 -100.00 0 -100.00 n/a n/a n/a
2023-02-13 2022-12-31 13F Merck CALL Call 509 -36.38 56 -18.84 n/a n/a n/a
2022-11-14 2022-09-30 13F Merck CALL Call 800 -25.86 69 -30.30 n/a n/a n/a
2022-08-12 2022-06-30 13F Merck CALL Call 1,079 99 n/a n/a n/a
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.