MarketAxess reports May volume rebound, adjusts market share estimates for reporting Anomalies
MarketAxess Holdings (NASDAQ:MKTX) saw a broad rebound in trading volumes across most product categories during May 2026, recovering from levels recorded in April.
The electronic trading platform provider reported that its estimated U.S. high-grade market share rose approximately 100 basis points month-over-month to 17.8%, a shift largely attributed to stronger performance in the platform’s client-initiated channel.
The company underscored that its market share figures are currently impacted by reporting anomalies in the broader industry.
MarketAxess estimates that duplicate trade reports inflated U.S. high-grade TRACE volumes by as much as 8% during the month.
If these figures were adjusted to align with recent FINRA proposals to suppress duplicate reporting, the company estimates its U.S. high-grade market share would have been approximately 19.5%—a 160-basis-point increase over its reported headline share.
Growth across several key execution protocols was a defining trend for the month, though this shift in product and protocol mix served as a primary driver for a month-over-month decline in the company’s total credit variable transaction fees per million (FPM).
Within the portfolio trading channel, total average daily volume (ADV) surged 47% to $2.1 billion.
This growth was anchored by record-breaking activity in U.S. high-grade portfolio trading, which saw ADV climb 68% to $1.4 billion.
U.S. high-yield and emerging markets also saw significant portfolio trading gains, rising 172% and 105%, respectively.
MarketAxess achieved a 22% estimated market share of U.S. credit portfolio trading, up from 16.8% in the same period a year ago.
The client-initiated channel also saw a 17% increase in total block trading ADV to $6 billion.
Within that segment, emerging markets block ADV grew by 35% to $2 billion, while U.S. credit block ADV rose 14% to $3.5 billion.
Conversely, eurobond block trading saw a 14% decline.
In the dealer-initiated channel, total Mid-X trading volume reached a record $7 billion, a 119% increase.