Exhibit 99.1 MarketAxess Reports Second Quarter 2025 Financial Results 11% Increase in Revenue to Record $219.5 Million; Strong Progress with New Initiatives to Drive Growth Record Block Trading ADV, Record Total Portfolio Trading ADV and Strong Growth in Dealer-Initiated ADV EPS of$1.91; $2.00 Excluding Notable Items 1 NEW YORK | August 6, 2025 - MarketAxess Holdings Inc. (Nasdaq: MKTX), the operator of a leading electronic trading platform for fixed-income securities, today announced financial results fo ...