Related Party Transactions and Outside Related Director Information

MarketAxess Holdings Inc. (MKTX)

5/1/2006 Proxy Information

Principal stockholder broker-dealer clients

Six of our broker-dealer clients or their affiliates each own more than five percent of the outstanding shares of our Common Stock. See “Security Ownership of Certain Beneficial Owners and Management.” These broker-dealer clients are: Banc of America Securities, Bear Stearns, Credit Suisse, Deutsche Bank, JPMorgan and Lehman Brothers (collectively, the “Principal Stockholder Broker-Dealer Clients”).

We have separate agreements with each of our broker-dealer clients including each of our Principal Stockholder Broker-Dealer Clients. These agreements govern each such broker-dealer’s access to, and activity on, our electronic trading platform. The term of the agreements is generally three years, with automatic annual renewal thereafter unless notice to terminate is given by a party at least thirty days prior to automatic renewal. Under each agreement, the broker-dealer is granted a worldwide, non-exclusive and non-transferable license to use our electronic trading platform. The broker-dealer agrees to supply us, on a non-exclusive basis, with one or more of the following: indicative prices and quantities of a minimum number of fixed-income instruments for our inventory pages; new issue descriptions and content; and credit research reports. These agreements also govern use of and access to our electronic trading platform. We may only provide the pricing, research and other content provided by a broker-dealer to those of our institutional investor clients approved by the broker-dealer to receive such content. Additionally, institutional investors must be approved by a broker-dealer before being able to engage in transactions on our platform. These agreements also provide for the fees and expenses to be paid by the broker-dealers for their use of our electronic trading platform.

We have historically earned a substantial portion of our revenues from our Principal Stockholder Broker-Dealer Clients. In particular, for the year ended December 31, 2005, $39.0 million (49.7% of our total revenues), were generated by our Principal Stockholder Broker-Dealer Clients.

Indemnification agreements

We have entered into an indemnification agreement with each of our outside directors. The indemnification agreements and our certificate of incorporation and bylaws require us to indemnify our directors and officers to the fullest extent permitted by Delaware law.

Registration rights agreement

Our Principal Stockholder Broker-Dealer Clients, along with certain other holders of our Common Stock, are party to our sixth amended and restated registration rights agreement. Stockholders who are a party to this agreement are provided certain rights to demand registration of shares of Common Stock and to participate in a registration of our Common Stock that we may decide to do, from time to time. Generally, we have agreed to pay all expenses of any registration pursuant to the registration rights agreement, except for underwriters’ discounts and commissions.

Appointment of one of our directors by one of our Principal Stockholder Broker-Dealer Clients

Mr. Hersch was originally appointed to our Board pursuant to the terms of an agreement among certain of our stockholders. This agreement terminated upon the initial public offering of our Common Stock.