<SEC-DOCUMENT>0001104659-18-022452.txt : 20180404
<SEC-HEADER>0001104659-18-022452.hdr.sgml : 20180404
<ACCEPTANCE-DATETIME>20180404171424
ACCESSION NUMBER:		0001104659-18-022452
CONFORMED SUBMISSION TYPE:	DEFA14A
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20180404
DATE AS OF CHANGE:		20180404
EFFECTIVENESS DATE:		20180404

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Interactive Brokers Group, Inc.
		CENTRAL INDEX KEY:			0001381197
		STANDARD INDUSTRIAL CLASSIFICATION:	SECURITY BROKERS, DEALERS & FLOTATION COMPANIES [6211]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		DEFA14A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33440
		FILM NUMBER:		18738111

	BUSINESS ADDRESS:	
		STREET 1:		ONE PICKWICK PLAZA
		CITY:			GREENWICH
		STATE:			CT
		ZIP:			06830
		BUSINESS PHONE:		203-618-5800

	MAIL ADDRESS:	
		STREET 1:		ONE PICKWICK PLAZA
		CITY:			GREENWICH
		STATE:			CT
		ZIP:			06830
</SEC-HEADER>
<DOCUMENT>
<TYPE>DEFA14A
<SEQUENCE>1
<FILENAME>a18-9602_1defa14a.htm
<DESCRIPTION>DEFA14A
<TEXT>


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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">UNITED STATES</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">SECURITIES   AND EXCHANGE COMMISSION</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Washington,   D.C. 20549</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="4" face="Times New Roman" style="font-size:14.0pt;font-weight:bold;">SCHEDULE 14A</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Proxy Statement   Pursuant to Section 14(a) of<br>   the Securities Exchange Act of 1934</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Filed by the Registrant&nbsp;&nbsp;</font><font face="Wingdings">x</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman"><font style="font-size:10.0pt;">Filed by a Party other than the Registrant</font>&nbsp;&nbsp;</font><font face="Wingdings">o</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Check the appropriate box:</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>    </td>
<td width="94%" colspan="3" valign="top" style="padding:0in .7pt 0in .7pt;width:94.96%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Preliminary Proxy Statement</font></p>    </td>   </tr>
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<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font> </p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Confidential, for Use of the Commission Only (as   permitted by Rule 14a-6(e)(2))</font></b></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>    </td>
<td width="94%" colspan="3" valign="top" style="padding:0in .7pt 0in .7pt;width:94.96%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Definitive Proxy Statement</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">x</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Definitive Additional Materials</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Soliciting Material under &#167;240.14a-12</font></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">INTERACTIVE BROKERS   GROUP, INC.</font></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Name of Registrant   as Specified In Its Charter)</font></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Name of Person(s)   Filing Proxy Statement, if other than the Registrant)</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Payment of Filing Fee (Check the appropriate box):</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">x</font></p>    </td>
<td width="94%" colspan="3" valign="top" style="padding:0in .7pt 0in .7pt;width:94.96%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">No fee required.</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>    </td>
<td width="94%" colspan="3" valign="top" style="padding:0in .7pt 0in .7pt;width:94.96%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Fee computed on table below per Exchange Act Rules 14a-6(i)(1)   and 0-11.</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(1)</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Title of each class of securities to which transaction applies:</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="90%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:90.3%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)</font></p>    </td>
<td width="90%" valign="top" style="padding:0in .7pt 0in .7pt;width:90.3%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Aggregate number of securities to which transaction applies:</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3)</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Per unit price or other underlying value of transaction computed   pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing   fee is calculated and state how it was determined):</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="4%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:4.66%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="90%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:90.3%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:4.66%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(4)</font></p>    </td>
<td width="90%" valign="top" style="padding:0in .7pt 0in .7pt;width:90.3%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Proposed maximum aggregate value of transaction:</font></p>    </td>   </tr>
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<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="4%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:4.66%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="90%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:90.3%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
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<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:4.66%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5)</font></p>    </td>
<td width="90%" valign="top" style="padding:0in .7pt 0in .7pt;width:90.3%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Total fee paid:</font></p>    </td>   </tr>
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<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="4%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:4.66%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="90%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:90.3%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr style="page-break-inside:avoid;">
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font></p>    </td>
<td width="94%" colspan="3" valign="top" style="padding:0in .7pt 0in .7pt;width:94.96%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Fee paid previously with preliminary materials.</font></p>    </td>   </tr>
<tr style="page-break-inside:avoid;">
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;">o</font> </p>    </td>
<td width="94%" colspan="3" valign="top" style="padding:0in .7pt 0in .7pt;width:94.96%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Check box if any part of the fee is offset as provided by   Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting   fee was paid previously. Identify the previous filing by registration statement   number, or the Form or Schedule and the date of its filing.</font></p>    </td>   </tr>
<tr>
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in .7pt 0in .7pt;width:4.36%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(1)</font></p>    </td>
<td width="90%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:90.6%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Amount Previously Paid:</font></p>    </td>   </tr>
<tr>
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in .7pt 0in .7pt;width:4.36%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="90%" colspan="2" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:90.6%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in .7pt 0in .7pt;width:4.36%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)</font></p>    </td>
<td width="90%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:90.6%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Form, Schedule or Registration Statement No.:</font></p>    </td>   </tr>
<tr>
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in .7pt 0in .7pt;width:4.36%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="90%" colspan="2" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:90.6%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in .7pt 0in .7pt;width:4.36%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3)</font></p>    </td>
<td width="90%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:90.6%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Filing Party:</font></p>    </td>   </tr>
<tr>
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in .7pt 0in .7pt;width:4.36%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="90%" colspan="2" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:90.6%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr>
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in .7pt 0in .7pt;width:4.36%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(4)</font></p>    </td>
<td width="90%" colspan="2" valign="top" style="padding:0in .7pt 0in .7pt;width:90.6%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Date Filed:</font></p>    </td>   </tr>
<tr>
<td width="5%" valign="top" style="padding:0in .7pt 0in .7pt;width:5.04%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="4%" valign="top" style="padding:0in .7pt 0in .7pt;width:4.36%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>
<td width="90%" colspan="2" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in .7pt 0in .7pt;width:90.6%;">
<p style="margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>    </td>   </tr>
<tr height="0">
<td width="36" style="border:none;"></td>
<td width="31" style="border:none;"></td>
<td width="2" style="border:none;"></td>
<td width="639" style="border:none;"></td>   </tr> </table>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<div style="margin:0in 0in .0001pt;"><hr size="3" width="100%" noshade align="left" style="color:#010101;"></div>
</div>
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<br clear="all" style="page-break-before:always;">
<div style="font-family:Times New Roman;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Supplemental Proxy Information for Proposal No.&nbsp;2 - To approve an amendment to the Company&#146;s 2007 Stock Incentive Plan to extend its term for a ten-year period through April&nbsp;24, 2027</font></b></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">This supplemental proxy information is being sent by Interactive Brokers Group,&nbsp;Inc. (the &#147;Company&#148;) to its stockholders to include, in a single supplement, certain information previously disclosed in the Company&#146;s Annual Report on Form&nbsp;10-K (the &#147;Annual Report&#148;), filed with the Securities Exchange Commission (&#147;SEC&#148;) on March&nbsp;1, 2018 and in the Company&#146;s Definitive Proxy Statement (the &#147;Proxy Statement&#148;), filed with the SEC on March&nbsp;8, 2018.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">In 2017, the Company amended the 2007 Stock Incentive Plan (&#147;Stock Incentive Plan&#148;) to extend its term for a ten year period through April&nbsp;24, 2027, pending stockholders&#146; approval at its 2018 Annual Meeting, as the current plan expired as of April&nbsp;24, 2017.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The Stock Incentive Plan provides that awards may be granted to directors, officers, contractors and consultants of the Company and its subsidiaries. </font>&#160;The purpose of the Stock Incentive Plan is to promote the Company&#146;s long-term financial success by attracting, retaining and rewarding eligible participants. As of December&nbsp;31, 2017, approximately 1,228 employees(1)&nbsp;of the Company, including the Company&#146;s executive officers, were eligible to participate in the Stock Incentive Plan. In addition, the Company&#146;s four non-employee directors were also eligible to participate in the Stock Incentive Plan.</p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">On December&nbsp;31, 2017, the Company granted 923,407 awards of restricted stock units(2)&nbsp;to eligible participants under the Stock Incentive Plan, of which 135,674(3)&nbsp;were granted to the Company&#146;s executive officers. These grants, were all subject to the stockholder approval of the extension of the Stock Incentive Plan contained in the Proxy Statement. The following table sets forth the equity-based awards (i.e., restricted stock units) that were granted on December&nbsp;31, 2017 under the Stock Incentive Plan to each of the Company&#146;s named executive officers, current executive officers, as a group, other employees who are not executive officers, as a group, and non-employee directors, as a group.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<table border="0" cellspacing="0" cellpadding="0" width="76%" style="border-collapse:collapse;">
<tr>
<td width="78%" valign="bottom" style="padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.26%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="13%" valign="bottom" style="padding:0in 0in 0in 0in;width:13.06%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Restricted</font></b></p>    </td>
<td width="5%" valign="bottom" style="padding:0in 0in 0in 0in;width:5.42%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>   </tr>
<tr>
<td width="78%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Name</font></b></p>    </td>
<td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.26%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>
<td width="13%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:13.06%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Stock&nbsp;Units(4)</font></b></p>    </td>
<td width="5%" valign="bottom" style="padding:0in 0in 0in 0in;width:5.42%;">
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Thomas Peterffy   - <i>Chairman and Chief Executive Officer</i></font></p>    </td>
<td width="3%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:3.26%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&#151;</font></p>    </td>
<td width="5%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:5.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5)</font></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" style="padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Earl H. Nemser -   <i>Vice Chairman and Director</i></font></p>    </td>
<td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.26%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" style="padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5,025</font></p>    </td>
<td width="5%" valign="bottom" style="padding:0in 0in 0in 0in;width:5.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5)</font></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Milan Galik - <i>President</i></font></p>    </td>
<td width="3%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:3.26%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">75,374</font></p>    </td>
<td width="5%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:5.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5)</font></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" style="padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Paul J. Brody - <i>Chief Financial Officer</i></font></p>    </td>
<td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.26%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" style="padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">40,200</font></p>    </td>
<td width="5%" valign="bottom" style="padding:0in 0in 0in 0in;width:5.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5)</font></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Thomas A. J.   Frank - <i>Executive Vice President and Chief Information   Officer</i></font></p>    </td>
<td width="3%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:3.26%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">15,075</font></p>    </td>
<td width="5%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:5.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5)</font></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" style="padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">All current   executive officers, as a group</font></p>    </td>
<td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.26%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" style="padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">135,674</font></p>    </td>
<td width="5%" valign="bottom" style="padding:0in 0in 0in 0in;width:5.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3)</font></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">All other   employees, as a group</font></p>    </td>
<td width="3%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:3.26%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">785,466</font></p>    </td>
<td width="5%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:5.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(6)</font></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" style="padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">All non-employee   directors, as a group (Gary Katz, the only non-employee director to receive a   grant on December&nbsp;31, 2017)</font></p>    </td>
<td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.26%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2,267</font></p>    </td>
<td width="5%" valign="bottom" style="padding:0in 0in 0.375pt 0in;width:5.42%;">
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(7)</font></p>    </td>   </tr>
<tr>
<td width="78%" valign="top" bgcolor="#CCEEFF" style="background:#CCEEFF;padding:0in 0in 0in 0in;width:78.26%;">
<p style="margin:0in 0in .0001pt 20.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Total</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
<td width="13%" valign="bottom" bgcolor="#CCEEFF" style="background:#CCEEFF;border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 0in 0in;width:13.06%;">
<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">923,407</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)</font></p>    </td>   </tr>  </table>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
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<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(1)&nbsp;</font> As previously disclosed in the Company&#146;s Annual Report in Item 1. &#151; Business under the caption &#147;Employees and Culture&#148;.</p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)&nbsp; As previously disclosed in the Company&#146;s Annual Report in Item 8. &#151; Financial Statements and Supplementary Data in Note 9 &#151; Employee Incentive Plans.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3)&nbsp; Sum of restricted stock units granted to the Company&#146;s named executive officers as previously disclosed in the Company&#146;s Proxy Statement in Item 1. &#151; Election of Directors under the caption &#147;Executive Compensation &#151; Grants of Plan-Based Stock Awards Table&#148;.</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(4)&nbsp;</font> Subject to receipt of stockholder approval of the extension of the Stock Incentive Plan, the Restricted Stock Units vest: (a)&nbsp;for employees, over a six year period, with 10% vesting on 5/9/2018 and 15% thereafter vesting on each of the first six anniversaries of 5/9/2018, and (b)&nbsp;for non-employee directors, over a five year period commencing one year after the date of the grant.</p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5)&nbsp; As previously disclosed in the Company&#146;s Proxy Statement in Item 1. &#151; Election of Directors under the caption &#147;Executive Compensation &#151; Grants of Plan-Based Stock Awards Table&#148;.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(6)&nbsp; Total shared granted less grants to all current executive officers, as a group and all non-employee directors, as a group (923,407 - 135,674 - 2,267).</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(7)&nbsp; As previously disclosed in the Company&#146;s Proxy Statement in Item 1. &#151; Election of Directors under the caption &#147;Executive Compensation &#151; Compensation of Directors&#148;.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">When considering the vote to approve the extension of the term of the Stock Incentive Plan, you should be aware that our directors and executive officers have interests in the proposal to extend the term of the Stock Incentive Plan that are different from, or in addition to, those of our stockholders, generally. </font>Each of the persons and groups listed in the table above has an interest in the proposal to extend the Stock Incentive Plan in respect of the restricted stock units so awarded and also stand to benefit from future awards under the Stock Incentive Plan if the term of the Stock Incentive Plan is extended.</p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Under the Stock Incentive Plan, up to 30 million shares have been authorized to be reserved for issuance to satisfy restricted stock units granted to eligible participants. As of December&nbsp;31, 2017 there were approximately 7,048,669(8)&nbsp;shares remaining for future issuance under the Stock Incentive Plan, pending stockholders&#146; approval at the Company&#146;s 2018 Annual Meeting.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">At the Company&#146;s 2018 Annual Meeting, the holders of Class&nbsp;A common stock and the Class&nbsp;B common stock will vote together as a single class on each of the proposals described in the Company&#146;s Proxy Statement. The holder of each share of the Class&nbsp;A common stock is entitled to one vote per share. Pursuant to our Amended and Restated Certificate of Incorporation, the holder of each share of the Class&nbsp;B common stock is entitled to 3,402,294 votes (that number equal to the number of membership interests in IBG&nbsp;LLC, the holding company for our businesses, such holder held on the record date divided by 100). Accordingly,&nbsp;IBG Holdings LLC (&#147;Holdings&#148;), as the sole holder of the Class&nbsp;B common stock, is expected to be entitled to approximately 340,229,444 votes in the aggregate, or approximately 82.6% of all votes eligible to be cast at the Annual Meeting(9).</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">It is expected that Holdings will vote its shares of Class&nbsp;B common stock, expected to constitute approximately 82.6% of all votes eligible to be cast at the Annual Meeting, in favor of the proposals. Accordingly, the voting power of Holdings alone is sufficient to assure the approval of the proposals(9).</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The Company has prepared this supplement, for good order&#146;s sake, to combine certain previously disclosed information in a single location. The Company does not believe that this supplement provides any material information that was not previously disclosed. Nevertheless, should any stockholder desire&nbsp;to change a vote previously provided by proxy, proxies may be revoked at any time prior to 11:59 p.m.&nbsp;EDT on April&nbsp;18, 2018 by entering your new vote electronically via the Internet at www.proxyvote.com using the account, control and pin numbers that you previously used or telephonically using the number indicated on your Voting Instruction Form. If you desire to change your vote by mail, you must first request paper copies of the materials and mail your new Voting Instruction Form&nbsp;using the prepaid return envelope previously provided. Your new instructions must be received before the close of business on April&nbsp;18, 2018.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">You may also revoke your proxy or change your vote at any time prior to the final tallying of votes by:</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.25in;"><font size="2" face="Symbol" style="font-size:10.0pt;">&#183;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>delivering a written notice of revocation to Paul J. Brody, the Secretary of the Company, at Interactive Brokers Group,&nbsp;Inc., One Pickwick Plaza, Greenwich, CT 06830;</p>
<p style="margin:0in 0in .0001pt .5in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.25in;"><font size="2" face="Symbol" style="font-size:10.0pt;">&#183;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>executing and delivering to the Corporate Secretary a later-dated proxy; or</p>
<p style="margin:0in 0in .0001pt .5in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.25in;"><font size="2" face="Symbol" style="font-size:10.0pt;">&#183;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>attending the meeting and voting in person.</p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(8)&nbsp; As previously disclosed in the Company&#146;s Annual Report in Item 5. &#151; Market for Registrant&#146;s Common Equity; Related Stockholder Matters and Issuer Purchases of Equity Securities under the caption &#147;Securities Authorized for Issuance under Equity Compensation Plans&#148;.</font></p>
<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(9)&nbsp; As previously disclosed in the Company&#146;s Proxy Statement in Voting Instructions and Information under the caption &#147;Who can vote at the Annual Meeting&#148;.</font></p>
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