Galik Milan

SEC source: 0001381197-26-000106 · ownership.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 3,215,389

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 8, 2026, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-26-000049 · ownership.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 3,470,428

F1 · shares: On January 22, 2026, Interactive Brokers Group, Inc.'s ("Issuer") Board of Directors ("Board") modified the compensation policy for members of the Board. The annual awards granted to all directors on December 31 of each year, under the 2007 Stock Incentive Plan as amended ("Plan"), increased from $25,000 to $50,000. This represents additional restricted stock units granted to the Reporting Person, under the Plan, which vested on January 1, 2026.

F2 · price: The price represents the closing price of the Issuer's Class A common stock on December 31, 2025.

F3 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-26-000022 · ownership.xml · nonDerivative · entry 2

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 3,470,039

F3 · shares: This represents an annual grant of restricted stock units under the Plan for being a member of the issuer's Board of Directors, which vested immediately on 12/31/2025.

F4 · price: The price represents the closing price of the issuer's Class A common stock on December 31, 2025.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-26-000022 · ownership.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 3,469,650

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2026 and 20% on each of the first four anniversaries of 5/9/2026.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2026 and 20% on each of the first four anniversaries of 5/9/2026.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-25-000162 · ownership.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Indirect · Immediate Family Member

Disclosed balance after: 0

F1 · shares: On June 17, 2025, the Issuer effected a four-for-one split of its common stock, resulting in the Reporting Person's indirect ownership of 671,766 additional shares of common stock.

F2 · shares: On December 29, 2025, an immediate family member of the Reporting Person transferred 895,688 shares of the Issuer's Class A common stock to an annuity trust of which the Reporting Person is not a beneficiary. The Reporting Person has no investment control over the securities in the trust and no longer has a pecuniary interest in those shares.

SEC source: 0001381197-25-000060 · form4.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 811,250

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 9, 2025, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-25-000003 · form4.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 805,383

F1 · shares: On December 31, 2024, the Reporting Person gifted 223,922 shares of Interactive Brokers Group, Inc.'s Class A common stock to an irrevocable grantor retained annuity trust of which the Reporting Person is a 100% beneficiary. The Reporting Person has no investment control over the securities in the trust.

F1 · price: On December 31, 2024, the Reporting Person gifted 223,922 shares of Interactive Brokers Group, Inc.'s Class A common stock to an irrevocable grantor retained annuity trust of which the Reporting Person is a 100% beneficiary. The Reporting Person has no investment control over the securities in the trust.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-25-000015 · form4.xml · nonDerivative · entry 2

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 874,830

F3 · shares: This represents an annual grant of restricted stock units under the Plan for being a member of the issuer's Board of Directors, which vested immediately on 12/31/2024.

F4 · price: The price represents the closing price of the issuer's Class A common stock on December 31, 2024.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-25-000015 · form4.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 874,688

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2025 and 20% on each of the first four anniversaries of 5/9/2025.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2025 and 20% on each of the first four anniversaries of 5/9/2025.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-24-000145 · form4.xml · nonDerivative · entry 2

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Indirect · Immediate Family Member

Disclosed balance after: 223,922

F1 · shares: On November 27, 2024, the reporting person transferred 223,922 shares of the Issuers Class A common stock to an immediate family member.

F3 · balance_after: Represents number of securities owned by an immediate family member in which the Reporting Person has a pecuniary interest.

SEC source: 0001381197-24-000145 · form4.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,029,305

F1 · shares: On November 27, 2024, the reporting person transferred 223,922 shares of the Issuers Class A common stock to an immediate family member.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-24-000103 · form4.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,253,227

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 9, 2024, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-24-000029 · form4.xml · nonDerivative · entry 2

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,315,182

F3 · shares: This represents an annual grant of restricted stock units under the Plan for being a member of the issuer's Board of Directors, which vested immediately on 12/31/2023.

F4 · price: The price represents the closing price of the issuer's Class A common stock on December 29, 2023.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-24-000029 · form4.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,314,880

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2024 and 20% on each of the first four anniversaries of 5/9/2024.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2024 and 20% on each of the first four anniversaries of 5/9/2024.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001381197-23-000034 · form4.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,179,402

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 9, 2023, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-23-000618 · doc1.xml · nonDerivative · entry 2

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,235,976

F3 · shares: This represents an annual grant of restricted stock units under the Plan for being a member of the issuer's Board of Directors, which vested immediately on 12/31/2022.

F4 · price: The price represents the closing price of the issuer's Class A common stock on December 30, 2022.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-23-000618 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,235,630

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2023 and 20% on each of the first four anniversaries of 5/9/2023.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2023 and 20% on each of the first four anniversaries of 5/9/2023.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-22-011701 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,099,688

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 9, 2022, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-22-009026 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,148,936

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2022 and 20% on each of the first four anniversaries of 5/9/2022.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2022 and 20% on each of the first four anniversaries of 5/9/2022.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-22-000742 · doc1.xml · nonDerivative · entry 2

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,148,745

F3 · shares: This represents an annual grant of restricted stock units under the Plan for being a member of the issuer's Board of Directors, which vested immediately on 12/31/2021.

F4 · price: The price represents the closing price of the issuer's Class A common stock on December 31, 2021, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-22-000742 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,148,430

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2022 and 20% on each of the first four anniversaries of 5/9/2022.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 20% on or about 5/9/2022 and 20% on each of the first four anniversaries of 5/9/2022.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-21-011040 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,038,213

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 7, 2021, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-21-000733 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,083,515

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 10% on or about 5/9/2021 and 15% on each of the first six anniversaries of 5/9/2021.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 10% on or about 5/9/2021 and 15% on each of the first six anniversaries of 5/9/2021.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-20-011434 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 970,204

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 8, 2020, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-20-000339 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,015,322

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 10% on 5/9/2020 and 15% on each of the first six anniversaries of 5/9/2020.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 10% on 5/9/2020 and 15% on each of the first six anniversaries of 5/9/2020.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-19-012250 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 900,662

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 9, 2019, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-19-000276 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 955,775

F1 · shares: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 10% on 5/9/2019 and 15% on each of the first six anniversaries of 5/9/2019.

F1 · price: This represents a grant of restricted stock units under the 2007 Stock Incentive Plan as amended ("Plan") that will vest 10% on 5/9/2019 and 15% on each of the first six anniversaries of 5/9/2019.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the Plan and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-18-003030 · doc1.xml · nonDerivative · entry 5

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 860,993

F1 · shares: These shares were purchased on behalf of the reporting person through a dividend reinvestment program, in which the reporting person is a participant. These shares were inadvertently excluded from Form 4 reporting.

F7 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $59.00 to $59.05, inclusive.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan"); (b) unvested restricted stock units that were awarded under the Plan; and (c) the cumulative shares purchased through the dividend investment program.

SEC source: 0001567619-18-003030 · doc1.xml · nonDerivative · entry 4

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 860,566

F1 · shares: These shares were purchased on behalf of the reporting person through a dividend reinvestment program, in which the reporting person is a participant. These shares were inadvertently excluded from Form 4 reporting.

F6 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $69.73 to $70.13, inclusive.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan"); (b) unvested restricted stock units that were awarded under the Plan; and (c) the cumulative shares purchased through the dividend investment program.

F8 · balance_after: The decrease in securities beneficially owned gives effect to the shares that were withheld for tax purposes related to the May 9, 2018 vesting of restricted stock units awarded under the Plan. This withholding transaction was reported on Form 4, filed with the Securities Exchange Commission on May 22, 2018.

SEC source: 0001140361-18-025203 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 858,865

F1 · price: The price represents the closing price of the issuer's Class A common stock as of May 9, 2018, the vesting date.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan") and (b) unvested restricted stock units that were awarded under the Plan.

SEC source: 0001567619-18-003030 · doc1.xml · nonDerivative · entry 3

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 926,466

F1 · shares: These shares were purchased on behalf of the reporting person through a dividend reinvestment program, in which the reporting person is a participant. These shares were inadvertently excluded from Form 4 reporting.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $72.02 to $72.44, inclusive.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan"); (b) unvested restricted stock units that were awarded under the Plan; and (c) the cumulative shares purchased through the dividend investment program.

SEC source: 0001140361-18-000583 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 925,125

F1 · shares: This represents a grant of restricted stock under the amended 2007 Stock Incentive Plan, pending stockholder approval, that will vest 10% on 5/9/2018 and 15% on each of the first six anniversaries of 5/9/2018.

F1 · price: This represents a grant of restricted stock under the amended 2007 Stock Incentive Plan, pending stockholder approval, that will vest 10% on 5/9/2018 and 15% on each of the first six anniversaries of 5/9/2018.

F2 · balance_after: These shares of Class A Common Stock are owned directly by the reporting person and represent the aggregate number of shares of restricted stock from awards granted under the 2007 Stock Incentive Plan since its inception, less vested shares that were withheld for tax purposes, or sold previously.

SEC source: 0001140361-18-017647 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 925,125

F1 · shares: This represents a grant of restricted stock units under the amended 2007 Stock Incentive Plan, pending stockholder approval, that will vest 10% on 5/9/2018 and 15% on each of the first six anniversaries of 5/9/2018.

F1 · price: This represents a grant of restricted stock units under the amended 2007 Stock Incentive Plan, pending stockholder approval, that will vest 10% on 5/9/2018 and 15% on each of the first six anniversaries of 5/9/2018.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the 2007 Stock Incentive Plan ("Plan"), (b) unvested restricted stock units that were awarded under the Plan, and (c) 75,374 restricted stock units that will be issued under the amended 2007 Stock Incentive Plan ("Amended Plan") subject to shareholder approval of the Amended Plan.

SEC source: 0001567619-18-003030 · doc1.xml · nonDerivative · entry 2

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 850,744

F1 · shares: These shares were purchased on behalf of the reporting person through a dividend reinvestment program, in which the reporting person is a participant. These shares were inadvertently excluded from Form 4 reporting.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $60.26 to $60.50, inclusive.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan"); (b) unvested restricted stock units that were awarded under the Plan; and (c) the cumulative shares purchased through the dividend investment program.

SEC source: 0001567619-18-003030 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 850,329

F1 · shares: These shares were purchased on behalf of the reporting person through a dividend reinvestment program, in which the reporting person is a participant. These shares were inadvertently excluded from Form 4 reporting.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $43.22 to $43.50, inclusive. The reporting person undertakes to provide Interactive Brokers Group, Inc. (the "Company"), any security holder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each price within the ranges set forth in footnotes (3) - (7) to this Form 4.

F2 · balance_after: This amount includes (a) Class A common stock attributable to vested restricted stock units that were awarded under the amended 2007 Stock Incentive Plan ("Plan"); (b) unvested restricted stock units that were awarded under the Plan; and (c) the cumulative shares purchased through the dividend investment program.

SEC source: 0001140361-17-020741 · doc1.xml · nonDerivative · entry 3

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 849,751

F1 · shares: An investment advisor hired by the reporting person inadvertently purchased / sold shares of IBKR as part of a broad based investment strategy.

F3 · balance_after: The reported amount also includes the shares sold by an investment advisor hired by the reporting person as part of a broad based investment strategy, as well as shares granted on December 31, 2016 under the 2007 Stock Incentive Plan, previously reported on Form 4 filed with the Securities Exchange Commission on January 4, 2017.

SEC source: 0001140361-17-000500 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 849,750

F1 · shares: This represents a grant of restricted stock that will vest 10% on 5/9/2017 and 15% on each of the first six anniversaries of 5/9/2017.

F1 · price: This represents a grant of restricted stock that will vest 10% on 5/9/2017 and 15% on each of the first six anniversaries of 5/9/2017.

F2 · balance_after: These shares of Class A Common Stock are owned directly by the reporting person and represent the aggregate number of shares of restricted stock from awards granted under the 2007 Stock Incentive Plan since its inception, less vested shares that were withheld for tax purposes, or sold previously.

SEC source: 0001140361-17-020741 · doc1.xml · nonDerivative · entry 2

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 734,954

F1 · shares: An investment advisor hired by the reporting person inadvertently purchased / sold shares of IBKR as part of a broad based investment strategy.

F2 · balance_after: These shares of Class A Common Stock are owned directly by the reporting person and represent the aggregate number of shares of restricted stock from awards granted under the 2007 Stock Incentive Plan since its inception, less vested shares that were withheld for tax purposes, or sold previously. The reported amount also includes the shares inadvertently purchased by an investment advisor hired by the reporting person as part of a broad based investment strategy.

SEC source: 0001140361-17-020741 · doc1.xml · nonDerivative · entry 1

Galik Milan · CIK 0001391404 · Director · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 734,953

F1 · shares: An investment advisor hired by the reporting person inadvertently purchased / sold shares of IBKR as part of a broad based investment strategy.

F2 · balance_after: These shares of Class A Common Stock are owned directly by the reporting person and represent the aggregate number of shares of restricted stock from awards granted under the 2007 Stock Incentive Plan since its inception, less vested shares that were withheld for tax purposes, or sold previously. The reported amount also includes the shares inadvertently purchased by an investment advisor hired by the reporting person as part of a broad based investment strategy.