X0206 3 2019-04-18 0 0001381197 Interactive Brokers Group, Inc. IBKR 0001602970 Echinus Advisors, LLC 63 CROSBY STREET 4TH FLOOR NEW YORK NY 10012 1 0 0 1 See Remarks 0001772442 Uhde Philip 63 CROSBY STREET, 4TH FLOOR NEW YORK NY 10012 1 0 0 1 See Remarks Class A Common Stock, par value $0.01 per share 2411525 I See footnote These securities are held for the account of Echinus Partners, LP, a Delaware limited partnership (the "Echinus Fund"). Echinus Advisors, LLC, a Delaware limited liability Company ("Echinus"), serves as the investment manager to the Echinus Fund. Mr. Philip Uhde ("Mr. Uhde") is the manager and majority controlling person of Echinus. In such capacities, each of Echinus and Mr. Uhde may be deemed to beneficially own the securities herein. Each Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his or its pecuniary interest therein, if any. Echinus may be deemed a director by deputization of the Issuer by virtue of the fact that Mr. Uhde, currently serves on the board of directors of the Issuer. /s/ Philip Uhde 2019-04-25 Echinus Advisors, LLC: by /s/ Philip Yang, its Chief Financial Officer & Chief Compliance Officer 2019-04-25