July 24, 2019

Paul J. Brody
Chief Financial Officer
Interactive Brokers Group, Inc.
One Pickwick Plaza
Greenwich, Connecticut 06830

       Re: Interactive Brokers Group, Inc.
           Form 10-K for Period Ending December 31, 2018
           Filed February 28, 2019
           Form 10-Q for Period Ending March 31, 2019
           Filed May 9, 2019
           CIK 0001381197

Dear Mr. Brody:

        We have reviewed your July 2, 2019 response to our comment letter and
have the
following comments. In some of our comments, we may ask you to provide us with
information
so we may better understand your disclosure.

       Please respond to these comments within ten business days by providing
the requested
information or advise us as soon as possible when you will respond. If you do
not believe our
comments apply to your facts and circumstances, please tell us why in your
response.

        After reviewing your response to these comments, we may have additional
comments. Unless we note otherwise, our references to prior comments are to
comments in our
July 2, 2019 letter.

Form 10-Q for the period ending March 31, 2019

Management's Discussion and Analysis of Financial Condition and Results of
Operations
Financial Overview, page 40

1.    We note your response to comment 2. Disclose, in future filings, how the
customer
      accounts related to the margin loan loss were "well margined" considering
you only
      recovered $5 million from the liquidation of collateral.
 Paul J. Brody
Interactive Brokers Group, Inc.
July 24, 2019
Page 2
Item 3. Quantitative and Qualitative Disclosures about Market Risk
Margin Loans, page 59

2.       We note your response to comment 2. Given that margin loans represent
a significant
         portion of total assets, the differing risk levels associated with
these types of loans as well
         as the events and circumstances which lead to the gross losses and
minimal recoveries
         recognized, please address the following in order to provide investors
with an enhanced
         understanding of the Company's exposures as it relates to the margin
loans:

             Disaggregate your margin loans by type, amount and underlying
strategy; and
             Disclose if you revised or enhanced your policies for margin loans
in response to
             the loss incurred.
       You may contact Michelle Miller at 202-551-3368 or Marc Thomas at
202-551-3452 if
you have questions regarding comments.



FirstName LastNamePaul J. Brody                                  Sincerely,
Comapany NameInteractive Brokers Group, Inc.
                                                                 Division of
Corporation Finance
July 24, 2019 Page 2                                             Office of
Financial Services
FirstName LastName