Mereo BioPharma Group plc - Depositary Receipt (Common Stock)
US ˙ NasdaqCM ˙ US5894921072

SecurityMREO / Mereo BioPharma Group plc - Depositary Receipt (Common Stock)
InstitutionSimplex Trading, Llc
Latest Disclosed Ownership0 shares
Latest Disclosed Value $ 0
Simplex Trading, Llc ownership in MREO / Mereo BioPharma Group plc - Depositary Receipt (Common Stock)

On May 14, 2026 - Simplex Trading, Llc filed a 13F-HR form disclosing ownership of 0 shares of Mereo BioPharma Group plc - Depositary Receipt (Common Stock) (US:MREO) valued at $0 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 11, 2026 disclosing 419,477 shares of Mereo BioPharma Group plc - Depositary Receipt (Common Stock). The current value of the position is $0 USD.

Simplex Trading, Llc has a history of taking positions in derivatives of the underlying security (MREO) in the form of stock options. The firm currently holds call options representing 203,100 of underlying shares valued at $67,023 USD and put options representing 53,400 of underlying shares valued at $17,622 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.

MREO / Mereo BioPharma Group plc - Depositary Receipt (Common Stock) 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 MEREO BIOPHARMA GROUP COM 589492107 0 -100.00 0
2026-02-11 2025-12-31 13F MEREO BIOPHARMA GROUP COM 589492107 419,477 223,208 113.73 175 0.0001
2025-11-12 2025-09-30 13F MEREO BIOPHARMA GROUP COM 589492107 196,269 -4,872 -2.42 0 0.0002
2025-08-05 2025-06-30 13F MEREO BIOPHARMA GROUP COM 589492107 201,141 197,024 4,785.62 1 0.0003
2025-05-12 2025-03-31 13F MEREO BIOPHARMA GROUP COM 589492107 4,117 -50,982 -92.53 0 0.0000
2025-02-11 2024-12-31 13F MEREO BIOPHARMA GROUP COM 589492107 55,099 21,244 62.75 0 0.0001
2024-11-08 2024-09-30 13F MEREO BIOPHARMA GROUP COM 589492107 33,855 -7,538 -18.21 0 0.0001
2024-07-25 2024-06-30 13F MEREO BIOPHARMA GROUP COM 589492107 41,393 12,151 41.55 0 0.0001
2024-04-25 2024-03-31 13F MEREO BIOPHARMA GROUP COM 589492107 29,242 29,242 0 0.0001
2023-04-27 2023-03-31 13F MEREO BIOPHARMA GROUP COM 589492107 0 -6,190 -100.00 0 0.0000
2023-02-02 2022-12-31 13F MEREO BIOPHARMA GROUP COM 589492107 6,190 4,328 232.44 0 -100.00 0.0000
2022-11-04 2022-09-30 13F MEREO BIOPHARMA GROUP COM 589492107 1,862 -69,124 -97.38 1 -98.73 0.0000
2022-08-03 2022-06-30 13F MEREO BIOPHARMA GROUP COM 589492107 70,986 69,977 6,935.28 79 7,800.00 0.0001
2022-05-02 2022-03-31 13F MEREO BIOPHARMA GROUP COM 589492107 1,009 -110,074 -99.09 1 -99.44 0.0000
2022-02-23 2021-12-31 13F/A-1 MEREO BIOPHARMA GROUP COM 589492107 111,083 99,670 873.30 177 405.71 0.0002
2022-02-04 2021-12-31 13F MEREO BIOPHARMA GROUP COM 589492107 11,413 0 35 0.0000
2021-10-28 2021-09-30 13F MEREO BIOPHARMA GROUP COM 589492107 11,413 -5,122 -30.98 35 -32.69 0.0000
2021-08-12 2021-06-30 13F MEREO BIOPHARMA GROUP COM 589492107 16,535 9,156 124.08 52 116.67 0.0001
2021-04-26 2021-03-31 13F MEREO BIOPHARMA GROUP COM 589492107 7,379 7,379 24 0.0000
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
(%)
2026-05-14 2026-03-31 13F MEREO BIOPHARMA GROUP CALL Call 203,100 21.40 67 -2.90 n/a n/a n/a
2026-02-11 2025-12-31 13F MEREO BIOPHARMA GROUP CALL Call 167,300 254.45 70 n/a n/a n/a
2025-11-12 2025-09-30 13F MEREO BIOPHARMA GROUP CALL Call 47,200 -76.31 0 n/a n/a n/a
2025-08-05 2025-06-30 13F MEREO BIOPHARMA GROUP CALL Call 199,200 250.09 1 n/a n/a n/a
2025-05-12 2025-03-31 13F MEREO BIOPHARMA GROUP CALL Call 56,900 210.93 0 n/a n/a n/a
2025-02-11 2024-12-31 13F MEREO BIOPHARMA GROUP CALL Call 18,300 -71.23 0 n/a n/a n/a
2024-11-08 2024-09-30 13F MEREO BIOPHARMA GROUP CALL Call 63,600 -14.97 0 n/a n/a n/a
2024-07-25 2024-06-30 13F MEREO BIOPHARMA GROUP CALL Call 74,800 35.75 0 n/a n/a n/a
2024-04-25 2024-03-31 13F MEREO BIOPHARMA GROUP CALL Call 55,100 -21.95 0 n/a n/a n/a
2024-02-02 2023-12-31 13F MEREO BIOPHARMA GROUP CALL Call 70,600 -10.75 0 n/a n/a n/a
2023-11-01 2023-09-30 13F MEREO BIOPHARMA GROUP CALL Call 79,100 40.25 0 n/a n/a n/a
2023-08-04 2023-06-30 13F MEREO BIOPHARMA GROUP CALL Call 56,400 68.86 0 n/a n/a n/a
2023-04-27 2023-03-31 13F MEREO BIOPHARMA GROUP CALL Call 33,400 802.70 0 n/a n/a n/a
2023-02-02 2022-12-31 13F MEREO BIOPHARMA GROUP CALL Call 3,700 -89.61 0 -100.00 n/a n/a n/a
2022-11-04 2022-09-30 13F MEREO BIOPHARMA GROUP CALL Call 35,600 105.78 30 57.89 n/a n/a n/a
2022-08-03 2022-06-30 13F MEREO BIOPHARMA GROUP CALL Call 17,300 1,341.67 19 1,800.00 n/a n/a n/a
2022-05-02 2022-03-31 13F MEREO BIOPHARMA GROUP CALL Call 1,200 -84.62 1 -95.83 n/a n/a n/a
2022-02-04 2021-12-31 13F MEREO BIOPHARMA GROUP CALL Call 7,800 0.00 24 0.00 n/a n/a n/a
2021-10-28 2021-09-30 13F MEREO BIOPHARMA GROUP CALL Call 7,800 0.00 24 0.00 n/a n/a n/a
2021-08-12 2021-06-30 13F MEREO BIOPHARMA GROUP CALL Call 7,800 540.39 24 -94.15 n/a n/a n/a
2021-04-26 2021-03-31 13F MEREO BIOPHARMA GROUP CALL Call 1,218 410 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
(%)
2026-05-14 2026-03-31 13F MEREO BIOPHARMA GROUP PUT Put 53,400 -90.89 18 -93.03 n/a n/a n/a
2026-02-11 2025-12-31 13F MEREO BIOPHARMA GROUP PUT Put 586,400 6,138.30 245 n/a n/a n/a
2025-11-12 2025-09-30 13F MEREO BIOPHARMA GROUP PUT Put 9,400 -62.40 0 n/a n/a n/a
2025-08-05 2025-06-30 13F MEREO BIOPHARMA GROUP PUT Put 25,000 7.76 0 n/a n/a n/a
2025-05-12 2025-03-31 13F MEREO BIOPHARMA GROUP PUT Put 23,200 -29.70 0 n/a n/a n/a
2025-02-11 2024-12-31 13F MEREO BIOPHARMA GROUP PUT Put 33,000 -2.08 0 n/a n/a n/a
2024-11-08 2024-09-30 13F MEREO BIOPHARMA GROUP PUT Put 33,700 28.14 0 n/a n/a n/a
2024-07-25 2024-06-30 13F MEREO BIOPHARMA GROUP PUT Put 26,300 -12.33 0 n/a n/a n/a
2024-04-25 2024-03-31 13F MEREO BIOPHARMA GROUP PUT Put 30,000 867.74 0 n/a n/a n/a
2024-02-02 2023-12-31 13F MEREO BIOPHARMA GROUP PUT Put 3,100 210.00 0 n/a n/a n/a
2023-11-01 2023-09-30 13F MEREO BIOPHARMA GROUP PUT Put 1,000 0.00 0 n/a n/a n/a
2023-08-04 2023-06-30 13F MEREO BIOPHARMA GROUP PUT Put 1,000 0 n/a n/a n/a
2023-04-27 2023-03-31 13F MEREO BIOPHARMA GROUP PUT Put 0 -100.00 0 n/a n/a n/a
2023-02-02 2022-12-31 13F MEREO BIOPHARMA GROUP PUT Put 100 -80.00 0 n/a n/a n/a
2022-11-04 2022-09-30 13F MEREO BIOPHARMA GROUP PUT Put 500 -44.44 0 -100.00 n/a n/a n/a
2022-08-03 2022-06-30 13F MEREO BIOPHARMA GROUP PUT Put 900 -40.00 1 0.00 n/a n/a n/a
2022-05-02 2022-03-31 13F MEREO BIOPHARMA GROUP PUT Put 1,500 -25.00 1 -66.67 n/a n/a n/a
2022-02-23 2021-12-31 13F/A MEREO BIOPHARMA GROUP PUT Put 2,000 -94.82 3 -97.52 n/a n/a n/a
2022-02-04 2021-12-31 13F MEREO BIOPHARMA GROUP PUT Put 38,600 121 n/a n/a n/a
2021-10-28 2021-09-30 13F MEREO BIOPHARMA GROUP PUT Put 38,600 0.00 121 -0.82 n/a n/a n/a
2021-08-12 2021-06-30 13F MEREO BIOPHARMA GROUP PUT Put 38,600 6,854.95 122 -34.76 n/a n/a n/a
2021-04-26 2021-03-31 13F MEREO BIOPHARMA GROUP PUT Put 555 187 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.