Anterix Inc.
US ˙ NasdaqCM ˙ US03676C1009

SecurityATEX / Anterix Inc.
InstitutionSimplex Trading, Llc
Latest Disclosed Ownership43,750 shares
Latest Disclosed Value $ 1,670,812
Simplex Trading, Llc ownership in ATEX / Anterix Inc.

On May 14, 2026 - Simplex Trading, Llc filed a 13F-HR form disclosing ownership of 43,750 shares of Anterix Inc. (US:ATEX) valued at $1,670,812 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 11, 2026 disclosing 22,550 shares of Anterix Inc.. This represents a change in shares of 94.01% during the quarter. The current value of the position is $2,927,750 USD.

Simplex Trading, Llc has a history of taking positions in derivatives of the underlying security (ATEX) in the form of stock options.

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.

ATEX / Anterix 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 ANTERIX COM 03676C100 43,750 21,200 94.01 1,671 239.43 0.0005
2026-02-11 2025-12-31 13F ANTERIX COM 03676C100 22,550 19,582 659.77 492 0.0003
2025-11-12 2025-09-30 13F ANTERIX COM 03676C100 2,968 2,968 0 0.0000
2025-08-05 2025-06-30 13F ANTERIX COM 03676C100 0 -12,634 -100.00 0 0.0000
2025-05-12 2025-03-31 13F ANTERIX COM 03676C100 12,634 12,511 10,171.54 0 0.0003
2025-02-11 2024-12-31 13F ANTERIX COM 03676C100 123 27 28.12 0 0.0000
2024-11-08 2024-09-30 13F ANTERIX COM 03676C100 96 96 0 0.0000
2024-07-25 2024-06-30 13F ANTERIX COM 03676C100 0 -13,667 -100.00 0 0.0000
2024-04-25 2024-03-31 13F ANTERIX COM 03676C100 13,667 9,216 207.05 0 0.0003
2024-02-02 2023-12-31 13F ANTERIX COM 03676C100 4,451 288 6.92 0 0.0001
2023-11-01 2023-09-30 13F ANTERIX COM 03676C100 4,163 3,598 636.81 0 0.0001
2023-08-04 2023-06-30 13F ANTERIX COM 03676C100 565 -4,503 -88.85 0 0.0000
2023-04-27 2023-03-31 13F ANTERIX COM 03676C100 5,068 3,362 197.07 0 0.0001
2023-02-02 2022-12-31 13F ANTERIX COM 03676C100 1,706 -978 -36.44 0 -100.00 0.0001
2022-11-04 2022-09-30 13F ANTERIX COM 03676C100 2,684 -1,139 -29.79 95 -39.49 0.0001
2022-08-03 2022-06-30 13F ANTERIX COM 03676C100 3,823 -5,696 -59.84 157 -71.51 0.0002
2022-05-02 2022-03-31 13F ANTERIX COM 03676C100 9,519 9,262 3,603.89 551 3,573.33 0.0005
2022-02-23 2021-12-31 13F/A-1 ANTERIX COM 03676C100 257 -15,590 -98.38 15 -98.42 0.0000
2022-02-04 2021-12-31 13F ANTERIX COM 03676C100 15,847 0 950 0.0004
2021-10-28 2021-09-30 13F ANTERIX COM 03676C100 15,847 0 0.00 950 0.00 0.0009
2021-08-12 2021-06-30 13F ANTERIX COM 03676C100 15,847 -1,441 -8.34 950 16.56 0.0009
2021-04-26 2021-03-31 13F ANTERIX COM 03676C100 17,288 10,124 141.32 815 -14.21 0.0015
2021-02-02 2020-12-31 13F ANTERIX COM 03676C100 7,164 1,397 24.22 0 -100.00 0.0000
2020-10-14 2020-09-30 13F ANTERIX COM 03676C100 5,767 -6,982 -54.77 0 -100.00
2020-07-13 2020-06-30 13F ANTERIX COM 03676C100 12,749 11,455 885.24 578 879.66 0.0009
2020-04-29 2020-03-31 13F ANTERIX COM 03676C100 1,294 775 149.33 59 168.18 0.0001
2020-02-05 2019-12-31 13F ANTERIX COM 03676C100 519 519 22 0.0000
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 ANTERIX PUT Put 700 -92.71 27 -87.56 n/a n/a n/a
2026-02-11 2025-12-31 13F ANTERIX PUT Put 9,600 1,500.00 210 n/a n/a n/a
2025-11-12 2025-09-30 13F ANTERIX PUT Put 600 -70.00 0 n/a n/a n/a
2025-08-05 2025-06-30 13F ANTERIX PUT Put 2,000 -85.19 0 n/a n/a n/a
2025-05-12 2025-03-31 13F ANTERIX PUT Put 13,500 6,650.00 0 n/a n/a n/a
2025-02-11 2024-12-31 13F ANTERIX PUT Put 200 -50.00 0 n/a n/a n/a
2024-11-08 2024-09-30 13F ANTERIX PUT Put 400 0.00 0 n/a n/a n/a
2024-07-25 2024-06-30 13F ANTERIX PUT Put 400 0 n/a n/a n/a
2024-04-25 2024-03-31 13F ANTERIX PUT Put 0 -100.00 0 n/a n/a n/a
2024-02-02 2023-12-31 13F ANTERIX PUT Put 1,100 1,000.00 0 n/a n/a n/a
2023-11-01 2023-09-30 13F ANTERIX PUT Put 100 0 n/a n/a n/a
2023-02-02 2022-12-31 13F ANTERIX PUT Put 0 -100.00 0 -100.00 n/a n/a n/a
2022-11-04 2022-09-30 13F ANTERIX PUT Put 200 -33.33 7 -41.67 n/a n/a n/a
2022-08-03 2022-06-30 13F ANTERIX PUT Put 300 12 n/a n/a n/a
2022-05-02 2022-03-31 13F ANTERIX PUT Put 0 -100.00 0 -100.00 n/a n/a n/a
2022-02-04 2021-12-31 13F ANTERIX PUT Put 5,200 0.00 312 0.00 n/a n/a n/a
2021-10-28 2021-09-30 13F ANTERIX PUT Put 5,200 4.00 312 4.35 n/a n/a n/a
2021-08-12 2021-06-30 13F ANTERIX PUT Put 5,000 4,285.96 299 -44.32 n/a n/a n/a
2021-04-26 2021-03-31 13F ANTERIX PUT Put 114 32.56 537 79.60 n/a n/a n/a
2021-02-02 2020-12-31 13F ANTERIX PUT Put 86 95.45 0 -100.00 n/a n/a n/a
2020-10-14 2020-09-30 13F ANTERIX PUT Put 44 -81.82 0 -100.00 n/a n/a n/a
2020-07-13 2020-06-30 13F ANTERIX PUT Put 242 374.51 1,097 372.84 n/a n/a n/a
2020-04-29 2020-03-31 13F ANTERIX PUT Put 51 292.31 232 314.29 n/a n/a n/a
2020-02-05 2019-12-31 13F ANTERIX PUT Put 13 56 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.