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MKTX · Marketaxess Holdings Inc

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Market Cap
$5.73B
Shares
35.19M

Institutional ownership from SEC Form 13F filings. Investment managers with more than $100 million in U.S. equities must disclose their positions every quarter, within 45 days of quarter-end, so the holdings shown can lag the market by up to a quarter.

Holders: 395
Total Value: $4,693,452,245
Total Shares: 41,360,721
Showing 1–100 of 411 holdings by value · page 1 of 5

Institutional Ownership Trend

26 quarters

Holder Concentration

Across 395 13F filers · Δ vs Mar 31, 2026
Top Holder
9.7%
Sep 2023 → Jun 2026 · range 9.7% – 12.4%
−0.9 pts
Top 5
36.2%
Sep 2023 → Jun 2026 · range 32.6% – 41.7%
−0.5 pts
Top 10
52.2%
Sep 2023 → Jun 2026 · range 50.0% – 58.5%
−2.3 pts
HHI
386
Sep 2023 → Jun 2026 · range 356 – 457
Broadly held−13

Quarterly Activity

vs Mar 31, 2026
New
56
Increased
131
Decreased
168
Sold Out
116
Unchanged
40
Holder count: -60
Institutional value: -26.1%
Shares held: +7.5%

Top Buyers

vs Mar 31, 2026
Institution Added Now Holds Open

Top Sellers

vs Mar 31, 2026
Institution Sold Now Holds Open

Top New Positions

vs Mar 31, 2026
Institution Acquired Value (USD) Open

Top Sold-Out Positions

vs Mar 31, 2026
Institution Previously Held Last Value (USD) Open
Showing 100 of 411
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Holder Value (USD) % of 13F Shares Open
Key facts CIK 1278021 CUSIP 57060D108 13F (30d) 331 filings 310 filers Visit website Investor relations