Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionWalleye Capital LLC
Latest Disclosed Ownership174,672 shares
Latest Disclosed Value $ 21,011,295
Walleye Capital LLC ownership in MRK / Merck & Co., Inc.

On May 13, 2026 - Walleye Capital LLC filed a 13F-HR/A form disclosing ownership of 174,672 shares of Merck & Co., Inc. (MX:MRK) valued at $21,011,295 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 90,774 shares of Merck & Co., Inc.. This represents a change in shares of 92.43% during the quarter.

Walleye Capital 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 104,700 of underlying shares valued at $12,594,363 USD and put options representing 76,300 of underlying shares valued at $9,178,127 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)
2026-05-13 2026-03-31 13F/A-1 MERCK COM 58933Y105 174,672 83,898 92.43 21,011 119.92 0.0874
2026-05-08 2026-03-31 13F MERCK COM 58933Y105 174,672 83,898 21,011 0.0874
2026-02-13 2025-12-31 13F MERCK COM 58933Y105 90,774 68,104 300.41 9,555 402.31 0.0293
2025-11-14 2025-09-30 13F MERCK COM 58933Y105 22,670 -30,272 -57.18 1,903 -54.61 0.0071
2025-08-13 2025-06-30 13F MERCK COM 58933Y105 52,942 -160,196 -75.16 4,191 -78.10 0.0163
2025-05-14 2025-03-31 13F MERCK COM 58933Y105 213,138 121,207 131.85 19,131 109.20 0.0863
2025-02-13 2024-12-31 13F MERCK COM 58933Y105 91,931 -271,279 -74.69 9,145 -77.83 0.0223
2024-11-14 2024-09-30 13F MERCK COM 58933Y105 363,210 112,653 44.96 41,246 32.97 0.0858
2024-08-14 2024-06-30 13F MERCK COM 58933Y105 250,557 3,820 1.55 31,019 -4.72 0.0553
2024-05-15 2024-03-31 13F MERCK COM 58933Y105 246,737 85,787 53.30 32,557 85.55 0.0580
2024-02-14 2023-12-31 13F MERCK COM 58933Y105 160,950 -44,792 -21.77 17,547 -17.16 0.0372
2023-11-21 2023-09-30 13F/A-1 MERCK COM 58933Y105 205,742 200,106 3,550.50 21,181 3,158.62 0.0542
2023-11-14 2023-09-30 13F MERCK COM 58933Y105 205,742 200,106 21,181 0.0545
2023-08-14 2023-06-30 13F MERCK COM 58933Y105 5,636 5,636 650 0.0024
2023-05-15 2023-03-31 13F MERCK COM 58933Y105 0 -225,102 -100.00 0 -100.00
2023-02-14 2022-12-31 13F MERCK COM 58933Y105 225,102 13,437 6.35 24,975 37.01 0.4554
2022-11-14 2022-09-30 13F MERCK COM 58933Y105 211,665 176,147 495.94 18,229 462.97 0.3479
2022-08-19 2022-06-30 13F/A-1 MERCK COM 58933Y105 35,518 35,518 3,238 0.0892
2022-08-08 2022-06-30 13F MERCK COM 58933Y105 35,518 35,518 3,238 0.0892
2020-11-16 2020-09-30 13F MERCK & CO. COM 58933Y105 0 -7,893 -100.00 0 -100.00
2020-08-14 2020-06-30 13F MERCK & CO. COM 58933Y105 7,893 7,893 610 0.1361
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
(%)
2026-05-13 2026-03-31 13F/A MERCK COM Call 104,700 -42.44 12,594 -34.22 n/a n/a n/a
2026-05-08 2026-03-31 13F MERCK COM Call 104,700 12,594 n/a n/a n/a
2026-02-13 2025-12-31 13F MERCK COM Call 181,900 -32.80 19,147 -15.73 n/a n/a n/a
2025-11-14 2025-09-30 13F MERCK COM Call 270,700 -19.39 22,720 -14.53 n/a n/a n/a
2025-08-13 2025-06-30 13F MERCK COM Call 335,800 114.71 26,582 89.35 n/a n/a n/a
2025-05-14 2025-03-31 13F MERCK COM Call 156,400 -39.82 14,038 -45.70 n/a n/a n/a
2025-02-13 2024-12-31 13F MERCK COM Call 259,900 -26.35 25,855 -35.49 n/a n/a n/a
2024-11-14 2024-09-30 13F MERCK COM Call 352,900 -17.68 40,075 -24.49 n/a n/a n/a
2024-08-14 2024-06-30 13F MERCK COM Call 428,700 -23.28 53,073 -28.02 n/a n/a n/a
2024-05-15 2024-03-31 13F MERCK COM Call 558,800 28.99 73,734 56.12 n/a n/a n/a
2024-02-14 2023-12-31 13F MERCK COM Call 433,200 190.54 47,227 207.69 n/a n/a n/a
2023-11-21 2023-09-30 13F/A MERCK COM Call 149,100 -28.21 15,350 -35.96 n/a n/a n/a
2023-11-14 2023-09-30 13F MERCK COM Call 149,100 15,350 n/a n/a n/a
2023-08-14 2023-06-30 13F MERCK COM Call 207,700 46.27 23,967 58.64 n/a n/a n/a
2023-05-15 2023-03-31 13F MERCK COM Call 142,000 154.03 15,107 143.58 n/a n/a n/a
2023-02-14 2022-12-31 13F MERCK COM Call 55,900 -32.97 6,202 -13.65 n/a n/a n/a
2022-11-14 2022-09-30 13F MERCK COM Call 83,400 7,182 n/a n/a n/a
2020-05-15 2020-03-31 13F MERCK COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2020-02-14 2019-12-31 13F MERCK COM Call 14,000 -88.86 1,273 -87.97 n/a n/a n/a
2019-11-14 2019-09-30 13F MERCK COM Call 125,700 105.73 10,581 106.54 n/a n/a n/a
2019-08-14 2019-06-30 13F MERCK COM Call 61,100 59.95 5,123 61.25 n/a n/a n/a
2019-08-14 2019-03-31 13F/A MERCK COM Call 38,200 461.76 3,177 559.13 n/a n/a n/a
2019-05-15 2019-03-31 13F MERCK COM Call 38,200 3,177 n/a n/a n/a
2018-11-14 2018-09-30 13F MERCK COM Call 6,800 482 n/a n/a n/a
Disclosed Put 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
(%)
2026-05-13 2026-03-31 13F/A MERCK COM Put 76,300 -77.59 9,178 -74.38 n/a n/a n/a
2026-05-08 2026-03-31 13F MERCK COM Put 76,300 9,178 n/a n/a n/a
2026-02-13 2025-12-31 13F MERCK COM Put 340,400 55.58 35,831 95.12 n/a n/a n/a
2025-11-14 2025-09-30 13F MERCK COM Put 218,800 -26.90 18,364 -22.49 n/a n/a n/a
2025-08-13 2025-06-30 13F MERCK COM Put 299,300 271.34 23,693 227.51 n/a n/a n/a
2025-05-14 2025-03-31 13F MERCK COM Put 80,600 -25.71 7,235 -32.98 n/a n/a n/a
2025-02-13 2024-12-31 13F MERCK COM Put 108,500 -33.23 10,794 -41.51 n/a n/a n/a
2024-11-14 2024-09-30 13F MERCK COM Put 162,500 4.64 18,454 -4.02 n/a n/a n/a
2024-08-14 2024-06-30 13F MERCK COM Put 155,300 -42.84 19,226 -46.37 n/a n/a n/a
2024-05-15 2024-03-31 13F MERCK COM Put 271,700 -1.74 35,851 18.93 n/a n/a n/a
2024-02-14 2023-12-31 13F MERCK COM Put 276,500 4.10 30,144 10.24 n/a n/a n/a
2023-11-21 2023-09-30 13F/A MERCK COM Put 265,600 85.86 27,344 65.83 n/a n/a n/a
2023-11-14 2023-09-30 13F MERCK COM Put 265,600 27,344 n/a n/a n/a
2023-08-14 2023-06-30 13F MERCK COM Put 142,900 1,034.13 16,489 1,130.52 n/a n/a n/a
2023-05-15 2023-03-31 13F MERCK COM Put 12,600 5.00 1,341 0.68 n/a n/a n/a
2023-02-14 2022-12-31 13F MERCK COM Put 12,000 -57.14 1,331 -44.79 n/a n/a n/a
2022-11-14 2022-09-30 13F MERCK COM Put 28,000 2,411 n/a n/a n/a
2020-05-15 2020-03-31 13F MERCK COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2020-02-14 2019-12-31 13F MERCK COM Put 10,800 500.00 982 546.05 n/a n/a n/a
2019-11-14 2019-09-30 13F MERCK COM Put 1,800 -76.92 152 -76.76 n/a n/a n/a
2019-08-14 2019-06-30 13F MERCK COM Put 7,800 3,800.00 654 3,747.06 n/a n/a n/a
2019-08-14 2019-03-31 13F/A MERCK COM Put 200 17 n/a n/a n/a
2019-05-15 2019-03-31 13F MERCK COM Put 200 17 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.