Merck & Co., Inc.
MX ˙ BMV ˙ US58933Y1055
SecurityMX:MRK / Merck & Co., Inc.
InstitutionGts Securities Llc
Latest Disclosed Ownership9,305 shares
Latest Disclosed Value $ 1,119,298
Gts Securities Llc ownership in MRK / Merck & Co., Inc.

On May 14, 2026 - Gts Securities Llc filed a 13F-HR form disclosing ownership of 9,305 shares of Merck & Co., Inc. (MX:MRK) valued at $1,119,298 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 33,094 shares of Merck & Co., Inc.. This represents a change in shares of -71.88% during the quarter.

Gts Securities 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 and put 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)
2026-05-14 2026-03-31 13F MERCK COM 58933Y105 9,305 -23,789 -71.88 1,119 -67.87 0.0396
2026-02-13 2025-12-31 13F MERCK COM 58933Y105 33,094 23,061 229.85 3,483 313.66 0.1188
2025-11-14 2025-09-30 13F MERCK COM 58933Y105 10,033 -2,852 -22.13 842 -17.37 0.0323
2025-08-08 2025-06-30 13F MERCK COM 58933Y105 12,885 -13,592 -51.34 1,020 -57.11 0.0455
2025-05-15 2025-03-31 13F MERCK COM 58933Y105 26,477 12,237 85.93 2,377 67.80 0.1029
2025-02-18 2024-12-31 13F MERCK COM 58933Y105 14,240 1,026 7.76 1,417 -5.60 0.0690
2024-11-13 2024-09-30 13F MERCK COM 58933Y105 13,214 -14,980 -53.13 1,501 -57.02 0.0033
2024-08-14 2024-06-30 13F MERCK COM 58933Y105 28,194 25,218 847.38 3,490 790.31 0.0074
2024-05-15 2024-03-31 13F MERCK COM 58933Y105 2,976 -39,277 -92.96 393 -91.49 0.0007
2024-02-15 2023-12-31 13F MERCK COM 58933Y105 42,253 35,623 537.30 4,606 575.37 0.0078
2023-11-15 2023-09-30 13F MERCK COM 58933Y105 6,630 6,630 683 0.0012
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
(%)
2025-02-18 2024-12-31 13F MERCK COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2024-11-13 2024-09-30 13F MERCK COM Call 122,800 26.60 13,945 16.13 n/a n/a n/a
2024-08-14 2024-06-30 13F MERCK COM Call 97,000 -66.83 12,009 -68.88 n/a n/a n/a
2024-05-15 2024-03-31 13F MERCK COM Call 292,400 96.11 38,582 137.37 n/a n/a n/a
2024-02-15 2023-12-31 13F MERCK COM Call 149,100 -36.34 16,255 -32.58 n/a n/a n/a
2023-11-15 2023-09-30 13F MERCK COM Call 234,200 24,111 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
(%)
2025-02-18 2024-12-31 13F MERCK COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2024-11-13 2024-09-30 13F MERCK COM Put 112,100 -8.04 12,730 -15.65 n/a n/a n/a
2024-08-14 2024-06-30 13F MERCK COM Put 121,900 -35.64 15,091 -39.61 n/a n/a n/a
2024-05-15 2024-03-31 13F MERCK COM Put 189,400 2.88 24,991 24.52 n/a n/a n/a
2024-02-15 2023-12-31 13F MERCK COM Put 184,100 -8.45 20,071 -3.06 n/a n/a n/a
2023-11-15 2023-09-30 13F MERCK COM Put 201,100 20,703 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.