X0306 4 2017-02-14 0 0001381197 Interactive Brokers Group, Inc. IBKR 0001391405 Peterffy Thomas PHILLIPS POINT EAST TOWER, SUITE 1001 777 S. FLAGLER DRIVE WEST PALM BEACH FL 33401 1 1 0 0 Chief Executive Officer Class A Common Stock 2017-02-14 4 A 0 104 38.77 A 104 D Class A Common Stock 2017-02-15 4 A 0 207 39.38 A 311 D An investment advisor hired by the reporting person inadvertently purchased shares of IBKR as part of a broad based investment strategy. This Form 4 is filed to report shares inadvertently purchased on February 14, 2017 and February 15, 2017. /s/ Thomas Peterffy 2017-05-10