Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionJennison Associates Llc
Latest Disclosed Ownership6,249,337 shares
Latest Disclosed Value $ 751,732,708
Jennison Associates Llc ownership in MRK / Merck & Co., Inc.

On May 6, 2026 - Jennison Associates Llc filed a 13F-HR form disclosing ownership of 6,249,337 shares of Merck & Co., Inc. (MX:MRK) valued at $751,732,708 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 30, 2026 disclosing 5,559,488 shares of Merck & Co., Inc.. This represents a change in shares of 12.41% during the quarter.

Jennison Associates Llc 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.

MX: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)
2026-05-06 2026-03-31 13F MERCK COM 58933Y105 6,249,337 689,849 12.41 751,733 28.46 0.5170
2026-01-30 2025-12-31 13F MERCK COM 58933Y105 5,559,488 5,559,488 585,192 0.3513
2025-01-24 2024-12-31 13F MERCK COM 58933Y105 0 -1,080,765 -100.00 0 -100.00
2024-11-08 2024-09-30 13F MERCK COM 58933Y105 1,080,765 -728,756 -40.27 122,732 -45.21 0.0762
2024-08-05 2024-06-30 13F MERCK COM 58933Y105 1,809,521 229,126 14.50 224,019 7.43 0.1436
2024-05-02 2024-03-31 13F MERCK COM 58933Y105 1,580,395 -20,623 -1.29 208,533 19.47 0.1394
2024-02-01 2023-12-31 13F MERCK COM 58933Y105 1,601,018 37,765 2.42 174,543 8.45 0.1301
2023-10-31 2023-09-30 13F MERCK COM 58933Y105 1,563,253 -55,015 -3.40 160,937 -13.81 0.1366
2023-08-03 2023-06-30 13F MERCK COM 58933Y105 1,618,268 430,320 36.22 186,732 47.75 0.1532
2023-04-26 2023-03-31 13F MERCK COM 58933Y105 1,187,948 -193,606 -14.01 126,386 -17.55 0.1159
2023-02-09 2022-12-31 13F MERCK COM 58933Y105 1,381,554 515,532 59.53 153,283 105.52 0.1553
2022-11-01 2022-09-30 13F MERCK COM 58933Y105 866,022 -773,717 -47.19 74,582 -50.11 0.0742
2022-08-02 2022-06-30 13F MERCK COM 58933Y105 1,639,739 1,489,602 992.16 149,495 1,113.53 0.1492
2022-05-11 2022-03-31 13F MERCK COM 58933Y105 150,137 150,137 12,319 0.0091
2021-02-05 2020-12-31 13F MERCK & CO. COM 58933Y105 0 -25,565 -100.00 0 -100.00
2020-11-04 2020-09-30 13F MERCK & CO. COM 58933Y105 25,565 -106,459 -80.64 2,121 -79.22 0.0017
2020-08-06 2020-06-30 13F MERCK & CO. COM 58933Y105 132,024 -540,663 -80.37 10,209 -80.28 0.0092
2020-05-06 2020-03-31 13F MERCK & CO. COM 58933Y105 672,687 -5,899 -0.87 51,757 -16.14 0.0629
2020-02-07 2019-12-31 13F MERCK COM 58933Y105 678,586 -292,958 -30.15 61,717 -24.54 0.0623
2019-11-08 2019-09-30 13F MERCK COM 58933Y105 971,544 -855,884 -46.84 81,785 -46.63 0.0864
2019-08-06 2019-06-30 13F MERCK COM 58933Y105 1,827,428 -11,008,666 -85.76 153,230 -85.65 0.1532
2019-05-10 2019-03-31 13F MERCK COM 58933Y105 12,836,094 -2,941,192 -18.64 1,067,578 -11.44 1.0609
2019-02-06 2018-12-31 13F MERCK COM 58933Y105 15,777,286 12,048,406 323.11 1,205,542 355.73 1.3487
2018-11-08 2018-09-30 13F MERCK COM 58933Y105 3,728,880 2,803,934 303.15 264,527 371.16 0.2436
2018-08-02 2018-06-30 13F MERCK COM 58933Y105 924,946 91,879 11.03 56,144 23.73 0.0547
2018-04-20 2018-03-31 13F MERCK COM 58933Y105 833,067 -148,654 -15.14 45,377 -17.86 0.0451
2018-01-25 2017-12-31 13F MERCK COM 58933Y105 981,721 -942,644 -48.98 55,241 -55.17 0.0546
2017-11-03 2017-09-30 13F MERCK COM 58933Y105 1,924,365 -19,604 -1.01 123,217 -1.10 0.1262
2017-08-04 2017-06-30 13F MERCK COM 58933Y105 1,943,969 -226,528 -10.44 124,589 -9.66 0.1322
2017-08-02 2017-03-31 13F/A-1 MERCK COM 58933Y105 2,170,497 -31,946 -1.45 137,913 6.37 0.1480
2017-04-28 2017-03-31 13F MERCK COM 58933Y105 2,170,497 2,170,497 137,913
2017-08-02 2016-12-31 13F/A-1 MERCK COM 58933Y105 2,202,443 -240,641 -9.85 129,658 -14.96 0.1448
2017-02-06 2016-12-31 13F MERCK COM 58933Y105 2,202,443 129,658
2016-11-01 2016-09-30 13F MERCK COM 58933Y105 2,443,084 44,529 1.86 152,473 10.34 0.1644
2016-08-03 2016-06-30 13F MERCK COM 58933Y105 2,398,555 -52,266 -2.13 138,181 6.56 0.1516
2016-05-03 2016-03-31 13F MERCK & CO INC COM 58933Y105 2,450,821 -724,201 -22.81 129,673 -22.68 0.1361
2016-02-10 2015-12-31 13F MERCK & CO INC COM 58933Y105 3,175,022 -3,160,118 -49.88 167,705 -46.40 0.1646
2015-11-06 2015-09-30 13F MERCK & CO INC COM 58933Y105 6,335,140 -1,205,526 -15.99 312,893 -27.11 0.3330
2015-08-03 2015-06-30 13F MERCK & CO INC COM 58933Y105 7,540,666 -148,324 -1.93 429,290 -2.87 0.3935
2015-06-25 2015-03-31 13F/A-1 MERCK & CO INC COM 58933Y105 7,688,990 1,143,786 17.48 441,963 18.90 0.4049
2015-05-04 2015-03-31 13F MERCK & CO INC COM 58933Y105 7,688,990 441,963
2015-06-25 2014-12-31 13F/A-1 MERCK & CO INC COM 58933Y105 6,545,204 -13,113,838 -66.71 371,702 -68.10 0.3476
2015-02-06 2014-12-31 13F MERCK & CO INC COM 58933Y105 6,545,204 -13,113,838 371,702 0.3476
2014-11-12 2014-09-30 13F/A-1 MERCK & CO INC COM 58933Y105 19,659,042 -213,973 -1.08 1,165,388 1.37 1.0810
2014-11-05 2014-09-30 13F MERCK & CO INC COM 58933Y105 19,659,042 -213,973 1,165,388 1.1103
2014-08-08 2014-06-30 13F MERCK & CO INC COM 58933Y105 19,873,015 -3,451,510 -14.80 1,149,654 -13.18 1.0562
2014-05-07 2014-03-31 13F MERCK & CO INC COM 58933Y105 23,324,525 11,195,348 92.30 1,324,133 118.12 1.2661
2014-02-10 2013-12-31 13F MERCK & CO INC COM 58933Y105 12,129,177 9,247,364 320.89 607,065 342.46 0.5955
2013-11-13 2013-09-30 13F MERCK & CO INC COM 58933Y105 2,881,813 -25,191 -0.87 137,203 1.61 0.1438
2013-08-05 2013-06-30 13F MERCK & CO INC COM 58933Y105 2,907,004 2,907,004 135,030 0.1519
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
(%)
2016-05-03 2016-03-31 13F MERCK & CO INC CALL OPTIONS Call 0 -100.00 0 -100.00 n/a n/a n/a
2016-02-10 2015-12-31 13F MERCK & CO INC CALL OPTIONS Call 650,000 0.00 34,333 6.94 n/a n/a n/a
2015-11-06 2015-09-30 13F MERCK & CO INC CALL OPTIONS Call 650,000 32,104 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.