Filing Details

1 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 Amendment No.: 1 Name of Issuer: Interactive Brokers Group Inc. Title of Class of Securities: Common Stock CUSIP Number: 45841N107 (Date of Event Which Requires Filing of this Statement) December 31, 2018 Check the appropriate box to designate the rule pursuant to which this Schedule is filed: /X/ Rule 13d-l(b) / / Rule 13d-l(c) / / Rule 13d-l(d) *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). CUSIP Number: 45841N107 1. Name of Reporting Person S.S. or I.R.S. Identification No. of Above Person Brian Bares 2. Check the Appropriate Box if a Member of a Group a. / / b. /X/ 3. SEC Use Only 4. Citizenship or Place of Organization USA Number of Shares Beneficially Owned by Each Reporting Person With: 5. Sole Voting Power: 60,000 6. Shared Voting Power: 6,929,471 7. Sole Dispositive Power: 60,000 8. Shared Dispositive Power: 6,929,471 9. Aggregate Amount Beneficially Owned by Each Reporting Person: 6,989,471 10. Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares / / 11. Percent of Class Represented by Amount in Row (9): 9.31% 12. Type of Reporting Person: IA, IN -3- Item 1(a) Name of Issuer: Interactive Brokers Group Inc. (b) Address of Issuer's Principal Executive Offices: One Pickwick Plaza Greenwich, CT 06830 Item 2(a) - (c). Name, Principal Business Address, and Citizenship of Persons Filing: Bares Capital Management, Inc. 12600 Hill Country Blvd, Suite R-230 Austin, TX 78738 USA (d) Title of Class of Securities: Common (e) CUSIP Number: 45841N107 Item 3. This statement is filed pursuant to Rule 13d-1(b)(1). /x/ Investment Adviser in accordance with Section 240.13d-1 (b)(1)(ii)(E) Item 4. Ownership. (a) Amount Beneficially Owned: Bares Capital Management, Inc. 6,929,471 Brian Bares 60,000 (b) Percent of Class: Bares Capital Management, Inc. 9.23% Brian Bares 9.31% (c) (i) shares with sole power to vote or direct the vote: Bares Capital Management, Inc. 0 shares Brian Bares 60,000 (ii) shared power to vote or direct the vote: Bares Capital Management, Inc. 6,929,471 Brian Bares 6,929,471 (iii) shares with sole power to dispose or to direct the disposition of: Bares Capital Management, Inc. 0 Brian Bares 60,000 (iv) shares with shared power to dispose or direct the disposition of: Bares Capital Management, Inc. 6,929,471 Brian Bares 6,929,471 Item 5. Ownership of Five Percent or Less of a Class. If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than 5 percent of the class of securities, check the following //. Item 6. Ownership of More than Five Percent on Behalf of Another Person. N/A -4-