MarketAxess Holdings Inc.
US ˙ NasdaqGS ˙ US57060D1081

SecurityMKTX / MarketAxess Holdings Inc.
InstitutionSei Investments Co
Latest Disclosed Ownership14,184 shares
Latest Disclosed Value $ 2,570,786
Sei Investments Co reports 3.50% decrease in ownership of MKTX / MarketAxess Holdings Inc.

On February 13, 2026 - Sei Investments Co filed a 13F-HR form disclosing ownership of 14,184 shares of MarketAxess Holdings Inc. (US:MKTX) valued at $2,570,850 USD as of December 31, 2025. The entity filed a previous 13F-HR on November 13, 2025 disclosing 14,698 shares of MarketAxess Holdings Inc.. This represents a change in shares of -3.50% during the quarter. The current value of the position is $1,744,348 USD.

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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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)
2026-02-13 2025-12-31 13F MARKETAXESS HLDGS COM 57060D108 14,184 -514 -3.50 2,571 0.35 0.0025
2025-11-13 2025-09-30 13F MARKETAXESS HLDGS COM 57060D108 14,698 -48,482 -76.74 2,561 -81.85 0.0028
2025-08-14 2025-06-30 13F MARKETAXESS HLDGS COM 57060D108 63,180 -64,456 -50.50 14,111 -48.90 0.0164
2025-05-14 2025-03-31 13F/A-1 MARKETAXESS HLDGS COM 57060D108 127,636 22,850 21.81 27,614 16.59 0.0355
2025-05-13 2025-03-31 13F MARKETAXESS HLDGS COM 57060D108 104,768 -18 23,681 0.0258
2025-02-11 2024-12-31 13F MARKETAXESS HLDGS COM 57060D108 104,786 -4,482 -4.10 23,686 -15.39 0.0304
2024-11-12 2024-09-30 13F MARKETAXESS HLDGS COM 57060D108 109,268 -2,589 -2.31 27,995 24.81 0.0364
2024-08-13 2024-06-30 13F MARKETAXESS HLDGS COM 57060D108 111,857 -47,287 -29.71 22,431 -35.72 0.0318
2024-05-07 2024-03-31 13F MARKETAXESS HLDGS COM 57060D108 159,144 -22,508 -12.39 34,892 -34.41 0.0511
2024-02-14 2023-12-31 13F MARKETAXESS HLDGS COM 57060D108 181,652 30,733 20.36 53,196 64.99 0.0854
2023-11-14 2023-09-30 13F MARKETAXESS HLDGS COM 57060D108 150,919 18,639 14.09 32,241 -6.76 0.0579
2023-08-11 2023-06-30 13F MARKETAXESS HLDGS COM 57060D108 132,280 -8,165 -5.81 34,579 -37.08 0.0603
2023-05-12 2023-03-31 13F MARKETAXESS HLDGS COM 57060D108 140,445 19,191 15.83 54,953 62.50 0.1021
2023-02-10 2022-12-31 13F MARKETAXESS HLDGS COM 57060D108 121,254 -27,746 -18.62 33,817 2.01 0.0751
2022-11-14 2022-09-30 13F MARKETAXESS HLDGS COM 57060D108 149,000 7,276 5.13 33,150 -8.64 0.0739
2022-08-15 2022-06-30 13F MARKETAXESS HLDGS COM 57060D108 141,724 54,073 61.69 36,285 22.00 0.0784
2022-05-13 2022-03-31 13F MARKETAXESS HLDGS COM 57060D108 87,651 70,941 424.54 29,741 340.41 0.0598
2022-02-14 2021-12-31 13F MARKETAXESS HLDGS COM 57060D108 16,710 9,860 143.94 6,753 143.44 0.0127
2021-11-12 2021-09-30 13F MARKETAXESS HLDGS COM 57060D108 6,850 694 11.27 2,774 1.28 0.0058
2021-08-06 2021-06-30 13F MARKETAXESS HLDGS COM 57060D108 6,156 -2,515 -29.00 2,739 -43.75 0.0061
2021-05-12 2021-03-31 13F MARKETAXESS HLDGS COM 57060D108 8,671 904 11.64 4,869 2.61 0.0123
2021-02-08 2020-12-31 13F MARKETAXESS HLDGS COM 57060D108 7,767 -2,895 -27.15 4,745 -3.18 0.0123
2020-12-04 2020-09-30 13F/A-1 MARKETAXESS HLDGS COM 57060D108 10,662 -5,123 -32.45 4,901 -40.38 0.0142
2020-11-06 2020-09-30 13F MARKETAXESS HLDGS COM 57060D108 13,236 -2,549 6,141 14,786.1626
2020-08-17 2020-06-30 13F/A-1 MARKETAXESS HLDGS COM 57060D108 15,785 -7,733 -32.88 8,221 5.25 0.0255
2020-08-11 2020-06-30 13F MARKETAXESS HLDGS COM 57060D108 17,451 -6,067 7,885 21,388.4822
2020-05-14 2020-03-31 13F MARKETAXESS HLDGS COM 57060D108 23,518 4,957 26.71 7,811 9.32 0.0287
2020-02-06 2019-12-31 13F MARKETAXESS HLDGS COM 57060D108 18,561 -3,862 -17.22 7,145 -3.52 0.0213
2019-11-12 2019-09-30 13F MARKETAXESS HLDGS COM 57060D108 22,423 -1,055 -4.49 7,406 -2.81 0.0189
2019-08-14 2019-06-30 13F MARKETAXESS HLDGS COM 57060D108 23,478 -46,177 -66.29 7,620 -54.99 0.0249
2019-05-15 2019-03-31 13F MARKETAXESS HLDGS COM 57060D108 69,655 23,874 52.15 16,929 101.54 0.0569
2019-02-13 2018-12-31 13F MARKETAXESS HLDGS COM 57060D108 45,781 2,837 6.61 8,400 10.98 0.0299
2018-11-08 2018-09-30 13F MARKETAXESS HLDGS COM 57060D108 42,944 -21,101 -32.95 7,569 -40.27 0.0274
2018-08-03 2018-06-30 13F MARKETAXESS HLDGS COM 57060D108 64,045 35,142 121.59 12,673 101.64 0.0431
2018-05-11 2018-03-31 13F MARKETAXESS HLDGS COM 57060D108 28,903 -3,724 -11.41 6,285 -4.53 0.0241
2018-02-08 2017-12-31 13F MARKETAXESS HLDGS COM 57060D108 32,627 3,943 13.75 6,583 24.40 0.0229
2017-11-06 2017-09-30 13F MARKETAXESS HLDGS COM 57060D108 28,684 1,978 7.41 5,292 -1.45 0.0188
2017-07-31 2017-06-30 13F MARKETAXESS HLDGS COM 57060D108 26,706 7,055 35.90 5,370 45.77 0.0214
2017-05-05 2017-03-31 13F MARKETAXESS HLDGS COM 57060D108 19,651 1,451 7.97 3,684 37.77 0.0161
2017-02-02 2016-12-31 13F MARKETAXESS HLDGS COM 57060D108 18,200 2,788 18.09 2,674 4.74 0.0129
2016-11-04 2016-09-30 13F MARKETAXESS HLDGS COM 57060D108 15,412 -9,040 -36.97 2,553 -28.21 0.0130
2016-08-11 2016-06-30 13F MARKETAXESS HLDGS COM 57060D108 24,452 -9,551 -28.09 3,556 -16.23 0.0213
2016-05-10 2016-03-31 13F/A-1 MARKETAXESS HLDGS COM 57060D108 34,003 -6,514 -16.08 4,245 -6.10 0.0264
2016-02-03 2015-12-31 13F MARKETAXESS HLDGS COM 57060D108 40,517 -38,460 -48.70 4,521 -38.36 0.0276
2015-11-02 2015-09-30 13F/A-1 MARKETAXESS HLDGS COM 57060D108 78,977 42,318 115.44 7,335 115.74 0.0673
2015-10-30 2015-09-30 13F DIREXION SHS ETF TR COM 57060D108 78,977 7,336
2015-08-07 2015-06-30 13F/A-1 MARKETAXESS HLDGS COM 57060D108 36,659 960 2.69 3,400 14.94 0.0307
2015-08-04 2015-06-30 13F MARKETAXESS HLDGS COM 57060D108 36,659 960 3,400 0.0307
2015-05-14 2015-03-31 13F/A-1 MARKETAXESS HLDGS COM 57060D108 35,699 22 0.06 2,958 15.64 0.0257
2015-05-01 2015-03-31 13F MARKETAXESS HLDGS COM 57060D108 35,699 2,958
2015-02-10 2014-12-31 13F MARKETAXESS HLDGS COM 57060D108 35,677 35,677 2,558 0.0226
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.