 NEW YORK, Oct. 05, 2021 GLOBE NEWSWIRE -- MarketAxess Holdings Inc. Nasdaq: MKTX, the operator of a leading electronic trading platform for fixed-income securities, and the provider of market data and post-trade services for the global fixed-income markets, today announced monthly trading volume for September 2021 of 559.5 billion consisting of 215.0 billion in credit volume and 344.5 billion in rates volume. 