A10 Networks, Inc.
US ˙ NYSE ˙ US0021211018

SecurityATEN / A10 Networks, Inc.
InstitutionSimplex Trading, Llc
Latest Disclosed Ownership11,717 shares
Latest Disclosed Value $ 270,897
Simplex Trading, Llc ownership in ATEN / A10 Networks, Inc.

On May 14, 2026 - Simplex Trading, Llc filed a 13F-HR form disclosing ownership of 11,717 shares of A10 Networks, Inc. (US:ATEN) valued at $270,897 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 11, 2026 disclosing 1,576 shares of A10 Networks, Inc.. This represents a change in shares of 643.46% during the quarter. The current value of the position is $368,382 USD.

Simplex Trading, Llc has a history of taking positions in derivatives of the underlying security (ATEN) in the form of stock options. The firm currently holds call options representing 100 of underlying shares valued at $2,312 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.

ATEN / A10 Networks, 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 A10 NETWORKS COM 002121101 11,717 10,141 643.46 271 900.00 0.0001
2026-02-11 2025-12-31 13F A10 NETWORKS COM 002121101 1,576 1,576 28 0.0000
2023-08-04 2023-06-30 13F A10 NETWORKS COM 002121101 0 -265 -100.00 0 0.0000
2023-04-27 2023-03-31 13F A10 NETWORKS COM 002121101 265 -1,058 -79.97 0 0.0000
2023-02-02 2022-12-31 13F A10 NETWORKS COM 002121101 1,323 1,323 0 0.0000
2022-08-03 2022-06-30 13F A10 NETWORKS COM 002121101 0 -21,153 -100.00 0 -100.00
2022-05-02 2022-03-31 13F A10 NETWORKS COM 002121101 21,153 -1,194 -5.34 295 -20.27 0.0003
2022-02-23 2021-12-31 13F/A-1 A10 NETWORKS COM 002121101 22,347 17,857 397.71 370 625.49 0.0004
2022-02-04 2021-12-31 13F A10 NETWORKS COM 002121101 4,490 0 51 0.0000
2021-10-28 2021-09-30 13F A10 NETWORKS COM 002121101 4,490 0 0.00 51 2.00 0.0000
2021-08-12 2021-06-30 13F A10 NETWORKS COM 002121101 4,490 -7,479 -62.49 50 -56.52 0.0000
2021-04-26 2021-03-31 13F A10 NETWORKS COM 002121101 11,969 3,179 36.17 115 33.72 0.0002
2021-02-02 2020-12-31 13F A10 NETWORKS COM 002121101 8,790 -25,448 -74.33 86 -60.55 0.0001
2020-10-14 2020-09-30 13F A10 NETWORKS COM 002121101 34,238 31,825 1,318.90 218 1,262.50 0.0003
2020-07-13 2020-06-30 13F A10 NETWORKS COM 002121101 2,413 2,413 -92.95 16 -92.66 0.0000
2020-02-05 2019-12-31 13F A10 NETWORKS COM 002121101 0 -16,731 -100.00 0 -100.00
2019-10-15 2019-09-30 13F A10 NETWORKS COM 002121101 16,731 -95,517 -85.09 116 -84.84 0.0003
2019-07-26 2019-06-30 13F A10 NETWORKS COM 002121101 112,248 17,161 18.05 765 13.50 0.0021
2019-04-18 2019-03-31 13F A10 NETWORKS COM 002121101 95,087 11,365 13.57 674 29.12 0.0019
2019-01-16 2018-12-31 13F A10 NETWORKS COM 002121101 83,722 58,996 238.60 522 248.00 0.0015
2018-10-23 2018-09-30 13F A10 NETWORKS COM 002121101 24,726 19,385 362.95 150 354.55 0.0005
2018-07-30 2018-06-30 13F A10 NETWORKS COM 002121101 5,341 4,943 1,241.96 33 1,550.00 0.0001
2018-04-26 2018-03-31 13F A10 NETWORKS COM 002121101 398 -4,002 -90.95 2 -93.94 0.0001
2018-01-10 2017-12-31 13F A10 NETWORKS COM 002121101 4,400 4,400 1,005.53 33 1,550.00 0.0014
2017-10-25 2017-09-30 13F A10 NETWORKS COM 002121101 0 -12 -100.00 0 -100.00 0.0000
2017-07-12 2017-06-30 13F A10 NETWORKS COM 002121101 12 -2,507 -99.52 0 -100.00
2017-04-21 2017-03-31 13F A10 NETWORKS COM 002121101 2,519 2,519 23 0.0010
2016-07-18 2016-06-30 13F A10 NETWORKS COM 002121101 0 -3,359 -100.00 0 -100.00
2016-04-14 2016-03-31 13F A10 NETWORKS COM 002121101 3,359 -14,637 -81.33 19 -83.90 0.0015
2016-01-20 2015-12-31 13F A10 NETWORKS COM 002121101 17,996 -1,075 -5.64 118 3.51 0.0092
2015-10-08 2015-09-30 13F A10 NETWORKS COM 002121101 19,071 19,071 114 0.0084
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 A10 NETWORKS CALL Call 100 -88.89 2 -86.67 n/a n/a n/a
2026-02-11 2025-12-31 13F A10 NETWORKS CALL Call 900 -71.88 16 n/a n/a n/a
2025-11-12 2025-09-30 13F A10 NETWORKS CALL Call 3,200 -84.00 0 n/a n/a n/a
2025-08-05 2025-06-30 13F A10 NETWORKS CALL Call 20,000 488.24 0 n/a n/a n/a
2025-05-12 2025-03-31 13F A10 NETWORKS CALL Call 3,400 78.95 0 n/a n/a n/a
2025-02-11 2024-12-31 13F A10 NETWORKS CALL Call 1,900 -93.75 0 n/a n/a n/a
2024-11-08 2024-09-30 13F A10 NETWORKS CALL Call 30,400 -15.32 0 n/a n/a n/a
2024-07-25 2024-06-30 13F A10 NETWORKS CALL Call 35,900 618.00 0 n/a n/a n/a
2024-04-25 2024-03-31 13F A10 NETWORKS CALL Call 5,000 -74.23 0 n/a n/a n/a
2024-02-02 2023-12-31 13F A10 NETWORKS CALL Call 19,400 -7.18 0 n/a n/a n/a
2023-11-01 2023-09-30 13F A10 NETWORKS CALL Call 20,900 260.34 0 n/a n/a n/a
2023-08-04 2023-06-30 13F A10 NETWORKS CALL Call 5,800 114.81 0 n/a n/a n/a
2023-04-27 2023-03-31 13F A10 NETWORKS CALL Call 2,700 -70.65 0 n/a n/a n/a
2023-02-02 2022-12-31 13F A10 NETWORKS CALL Call 9,200 -83.21 0 -100.00 n/a n/a n/a
2022-11-04 2022-09-30 13F A10 NETWORKS CALL Call 54,800 6.41 727 -1.76 n/a n/a n/a
2022-08-03 2022-06-30 13F A10 NETWORKS CALL Call 51,500 1,509.38 740 1,581.82 n/a n/a n/a
2022-05-02 2022-03-31 13F A10 NETWORKS CALL Call 3,200 77.78 44 51.72 n/a n/a n/a
2022-02-23 2021-12-31 13F/A A10 NETWORKS CALL Call 1,800 -93.73 29 -91.13 n/a n/a n/a
2022-02-04 2021-12-31 13F A10 NETWORKS CALL Call 28,700 327 n/a n/a n/a
2021-10-28 2021-09-30 13F A10 NETWORKS CALL Call 28,700 0.00 327 1.24 n/a n/a n/a
2021-08-12 2021-06-30 13F A10 NETWORKS CALL Call 28,700 12,217.60 323 44.84 n/a n/a n/a
2021-04-26 2021-03-31 13F A10 NETWORKS CALL Call 233 -22.33 223 -24.41 n/a n/a n/a
2021-02-02 2020-12-31 13F A10 NETWORKS CALL Call 300 -12.54 295 35.32 n/a n/a n/a
2020-10-14 2020-09-30 13F A10 NETWORKS CALL Call 343 1,533.33 218 1,457.14 n/a n/a n/a
2020-07-13 2020-06-30 13F A10 NETWORKS CALL Call 21 -38.24 14 -33.33 n/a n/a n/a
2020-04-29 2020-03-31 13F A10 NETWORKS CALL Call 34 183.33 21 162.50 n/a n/a n/a
2020-02-05 2019-12-31 13F A10 NETWORKS CALL Call 12 -84.00 8 -84.62 n/a n/a n/a
2019-10-15 2019-09-30 13F A10 NETWORKS CALL Call 75 294.74 52 333.33 n/a n/a n/a
2019-07-26 2019-06-30 13F A10 NETWORKS CALL Call 19 -74.67 12 -76.92 n/a n/a n/a
2019-01-16 2018-12-31 13F A10 NETWORKS CALL Call 0 -100.00 0 -100.00 n/a n/a n/a
2018-10-23 2018-09-30 13F A10 NETWORKS CALL Call 63 250.00 38 245.45 n/a n/a n/a
2018-07-30 2018-06-30 13F A10 NETWORKS CALL Call 18 12.50 11 -71.05 n/a n/a n/a
2018-04-26 2018-03-31 13F A10 NETWORKS CALL Call 16 -11.11 0 -100.00 n/a n/a n/a
2018-01-10 2017-12-31 13F A10 NETWORKS CALL Call 0 -100.00 0 n/a n/a n/a
2017-10-25 2017-09-30 13F A10 NETWORKS CALL Call 4 0 n/a n/a n/a
2017-01-11 2016-12-31 13F A10 NETWORKS CALL Call 0 -100.00 0 -100.00 n/a n/a n/a
2016-10-07 2016-09-30 13F A10 NETWORKS CALL Call 352 576.92 40 1,900.00 n/a n/a n/a
2016-07-18 2016-06-30 13F A10 NETWORKS CALL Call 52 2,500.00 2 -95.00 n/a n/a n/a
2016-04-14 2016-03-31 13F A10 NETWORKS CALL Call 2 -96.15 0 -100.00 n/a n/a n/a
2015-07-08 2015-06-30 13F A10 NETWORKS CALL Call 0 -100.00 0 -100.00 n/a n/a n/a
2015-04-21 2015-03-31 13F A10 NETWORKS CALL Call 55 266.67 6 n/a n/a n/a
2015-03-04 2014-12-31 13F A10 NETWORKS CALL Call 15 0 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
(%)
2026-02-11 2025-12-31 13F A10 NETWORKS PUT Put 0 -100.00 0 n/a n/a n/a
2025-11-12 2025-09-30 13F A10 NETWORKS PUT Put 2,900 -19.44 0 n/a n/a n/a
2025-08-05 2025-06-30 13F A10 NETWORKS PUT Put 3,600 100.00 0 n/a n/a n/a
2025-05-12 2025-03-31 13F A10 NETWORKS PUT Put 1,800 1,700.00 0 n/a n/a n/a
2025-02-11 2024-12-31 13F A10 NETWORKS PUT Put 100 0 n/a n/a n/a
2024-11-08 2024-09-30 13F A10 NETWORKS PUT Put 0 -100.00 0 n/a n/a n/a
2024-07-25 2024-06-30 13F A10 NETWORKS PUT Put 200 -88.89 0 n/a n/a n/a
2024-04-25 2024-03-31 13F A10 NETWORKS PUT Put 1,800 800.00 0 n/a n/a n/a
2024-02-02 2023-12-31 13F A10 NETWORKS PUT Put 200 -50.00 0 n/a n/a n/a
2023-11-01 2023-09-30 13F A10 NETWORKS PUT Put 400 -77.78 0 n/a n/a n/a
2023-08-04 2023-06-30 13F A10 NETWORKS PUT Put 1,800 100.00 0 n/a n/a n/a
2023-04-27 2023-03-31 13F A10 NETWORKS PUT Put 900 -84.48 0 n/a n/a n/a
2023-02-02 2022-12-31 13F A10 NETWORKS PUT Put 5,800 20.83 0 -100.00 n/a n/a n/a
2022-11-04 2022-09-30 13F A10 NETWORKS PUT Put 4,800 -46.07 63 -50.39 n/a n/a n/a
2022-08-03 2022-06-30 13F A10 NETWORKS PUT Put 8,900 36.92 127 41.11 n/a n/a n/a
2022-05-02 2022-03-31 13F A10 NETWORKS PUT Put 6,500 182.61 90 136.84 n/a n/a n/a
2022-02-23 2021-12-31 13F/A A10 NETWORKS PUT Put 2,300 -50.00 38 -26.92 n/a n/a n/a
2022-02-04 2021-12-31 13F A10 NETWORKS PUT Put 4,600 52 n/a n/a n/a
2021-10-28 2021-09-30 13F A10 NETWORKS PUT Put 4,600 0.00 52 1.96 n/a n/a n/a
2021-08-12 2021-06-30 13F A10 NETWORKS PUT Put 4,600 15,762.07 51 88.89 n/a n/a n/a
2021-04-26 2021-03-31 13F A10 NETWORKS PUT Put 29 -71.57 27 -73.00 n/a n/a n/a
2021-02-02 2020-12-31 13F A10 NETWORKS PUT Put 102 67.21 100 163.16 n/a n/a n/a
2020-10-14 2020-09-30 13F A10 NETWORKS PUT Put 61 577.78 38 533.33 n/a n/a n/a
2020-07-13 2020-06-30 13F A10 NETWORKS PUT Put 9 -85.25 6 -84.21 n/a n/a n/a
2020-02-05 2019-12-31 13F A10 NETWORKS PUT Put 0 -100.00 0 -100.00 n/a n/a n/a
2019-10-15 2019-09-30 13F A10 NETWORKS PUT Put 118 -92.94 81 -92.89 n/a n/a n/a
2019-07-26 2019-06-30 13F A10 NETWORKS PUT Put 1,672 3.66 1,140 -0.26 n/a n/a n/a
2019-04-18 2019-03-31 13F A10 NETWORKS PUT Put 1,613 66.46 1,143 89.24 n/a n/a n/a
2019-01-16 2018-12-31 13F A10 NETWORKS PUT Put 969 33.29 604 36.65 n/a n/a n/a
2018-10-23 2018-09-30 13F A10 NETWORKS PUT Put 727 786.59 442 766.67 n/a n/a n/a
2018-07-30 2018-06-30 13F A10 NETWORKS PUT Put 82 2,633.33 51 -88.46 n/a n/a n/a
2018-04-26 2018-03-31 13F A10 NETWORKS PUT Put 3 50.00 0 -100.00 n/a n/a n/a
2018-01-10 2017-12-31 13F A10 NETWORKS PUT Put 2 -33.33 0 n/a n/a n/a
2017-01-11 2016-12-31 13F A10 NETWORKS PUT Put 0 -100.00 0 n/a n/a n/a
2016-10-07 2016-09-30 13F A10 NETWORKS PUT Put 25 0 n/a n/a n/a
2016-07-18 2016-06-30 13F A10 NETWORKS PUT Put 0 -100.00 0 -100.00 n/a n/a n/a
2016-04-14 2016-03-31 13F A10 NETWORKS PUT Put 30 -72.97 11 -8.33 n/a n/a n/a
2016-01-20 2015-12-31 13F A10 NETWORKS PUT Put 111 54.17 12 300.00 n/a n/a n/a
2015-10-08 2015-09-30 13F A10 NETWORKS PUT Put 72 3 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.