Interactive Brokers files prospectus for 2,499,567 shares

Interactive Brokers Group, Inc. filed a Prospectus Supplement under Rule 424(b)(5) on July 31, 2026 to take down 2,499,567 shares of its common stock from its shelf Registration Statement on Form S-3 (Registration No. 333-297857).

Rhea-AI Filing Summary

Interactive Brokers Group, Inc. filed a Prospectus Supplement under Rule 424(b)(5) on July 31, 2026 to take down 2,499,567 shares of its common stock from its shelf Registration Statement on Form S-3 (Registration No. 333-297857).

The company also filed an opinion from Dechert LLP regarding the validity of these shares as Exhibit 5.2, and that opinion is incorporated by reference into the Form S-3 registration statement. An Inline XBRL cover page data file is included as Exhibit 104.

Filing Explained

The filing documents a 2,499,567-share shelf takedown, but no sale, proceeds, or ownership change is established.

This 8-K reports the company’s July 31, 2026 filing of a prospectus supplement for 2,499,567 shares from its Form S-3 shelf; it documents a registration step, not an evidenced completed sale or proceeds receipt.

The related active shelf permits future primary Class A common-stock offerings, so the consequence for existing holders is potential future issuance rather than an established ownership change in this filing.

A 424(b)(5) supplement is intended to state final terms of a specific takedown, but this 8-K provides no price, fees, cash proceeds, use of proceeds, or issuance result.

The active shelf record lists an expiration date of July 31, 2029; a later prospectus supplement would be the document to check for the offering’s price, fees, and final terms.

8-K Event Classification

2 items: 8.01, 9.01

2 items

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, or exhibit attachments filed with this report.

Key Figures

Shares covered by prospectus supplement: 2,499,567 shares Registration Statement No.: 333-297857 Prospectus Supplement rule: Rule 424(b)(5) +1 more

4 metrics

Shares covered by prospectus supplement 2,499,567 shares Common stock taken down from Form S-3 shelf registration

Registration Statement No. 333-297857 Form S-3 shelf registration referenced for the takedown

Prospectus Supplement rule Rule 424(b)(5) SEC rule under which the Prospectus Supplement was filed

Prospectus Supplement filing date July 31, 2026 Date Interactive Brokers filed the Prospectus Supplement

Key Terms

Prospectus Supplement, Rule 424(b)(5), shelf Registration Statement, Form S-3, +1 more

5 terms

Prospectus Supplement regulatory

"filed a Prospectus Supplement under Rule 424(b)(5) to take down"

A prospectus supplement is an additional document provided alongside a company's main offering details, offering updated or extra information about a specific financial product being sold. It helps investors understand the latest terms, risks, and details of the investment, similar to how an update or revision clarifies or expands on original instructions, ensuring they have current and complete information before making a decision.

Rule 424(b)(5) regulatory

"Prospectus Supplement under Rule 424(b)(5) to take down"

shelf Registration Statement regulatory

"to take down 2,499,567 shares off its shelf Registration Statement"

A shelf registration statement is a document a company files with regulators that allows it to sell shares or bonds quickly when it’s a good time to raise money. It’s like having a pre-approved plan ready so the company can act fast without going through lengthy paperwork each time they want to sell, making fundraising more flexible.

Form S-3 regulatory

"shelf Registration Statement on Form S-3 (Registration No. 333-297857)"

Form S-3 is a legal document companies use to register their stock sales with the government, making it easier and faster for them to raise money by selling shares to investors. It’s like having a pre-approved shopping list that lets a company quickly sell new shares when they need funds, without going through a lengthy approval process each time.

Inline XBRL technical

"the cover page XBRL tags are embedded within the Inline XBRL Document"

Inline XBRL is a file format for financial filings that embeds machine-readable data tags directly inside the human-readable report, so the same document can be read by people and parsed by software. For investors it makes extracting, comparing and verifying financial numbers faster and more reliable—like a grocery list where each item also has a barcode—reducing manual errors and speeding up analysis.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Interactive Brokers Group (IBKR) disclose in this 8-K?

Interactive Brokers Group filed a Prospectus Supplement under Rule 424(b)(5) to take down 2,499,567 shares of its common stock from an existing Form S-3 shelf registration, and included related legal and data exhibits.

How many shares are covered by the new Prospectus Supplement for IBKR?

The Prospectus Supplement covers 2,499,567 shares of Interactive Brokers Group common stock. These shares are being taken down from the company’s existing shelf Registration Statement on Form S-3, referenced as Registration No. 333-297857.

Which registration statement does Interactive Brokers (IBKR) reference for this takedown?

Interactive Brokers references its shelf Registration Statement on Form S-3, Registration No. 333-297857. The Prospectus Supplement under Rule 424(b)(5) takes down 2,499,567 shares of common stock from this existing shelf.

What legal opinion is associated with Interactive Brokers (IBKR) Prospectus Supplement?

The company filed a legal opinion from Dechert LLP as Exhibit 5.2. This opinion addresses the validity of the 2,499,567 common shares covered by the Prospectus Supplement and is incorporated by reference into the Form S-3 registration statement.

What exhibits are included with Interactive Brokers (IBKR) 8-K related to the Prospectus Supplement?

The 8-K lists Exhibit 5.2, an opinion of Dechert LLP on the validity of the shares, and Exhibit 104, the Cover Page Interactive Data File, with XBRL tags embedded within the Inline XBRL document.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 07/31/2026 - 01:03 PM Accepted by SEC EDGAR 07/31/2026 - 01:02 PM Learn about SEC filing dates

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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): July 31, 2026

Interactive Brokers Group, Inc.

(Exact name of Registrant as Specified in Its Charter)

Delaware			001-33440	30-0390693
(State or Other Jurisdiction of Incorporation)			(Commission File Number)	(IRS Employer Identification No.)
ONE PICKWICK PLAZA
GREENWICH, Connecticut				06830
(Address of Principal Executive Offices)				(Zip Code)

Registrant’s Telephone Number, Including Area Code: 203 618-5800

,

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, par value $.01 per share		IBKR		The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events.

On July 31, 2026, Interactive Brokers Group, Inc. (the “Company”) filed a Prospectus Supplement under Rule 424(b)(5) to take down 2,499,567 shares of the Company’s common stock off its shelf Registration Statement on Form S-3 (Registration Statement No. 333-297857) (the “Registration Statement”) filed with the SEC on July 31, 2026. The legal opinion letter of Dechert LLP, counsel to the Company, regarding the validity of the shares is filed as Exhibit 5.2 to this Current Report on Form 8-K. The legal opinion letter is also hereby incorporated by reference into the Registration Statement, as Exhibit 5.2 thereto.

Item 9.01 Financial Statements and Exhibits.

Exhibit No.		Description
5.2		Opinion of Dechert
104		Cover Page Interactive Data File (the cover page XBRL tags are embedded within the Inline XBRL Document).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date:	July 31, 2026	By:	/s/ Paul J. Brody
			Paul J Brody Chief Financial Officer, Treasurer and Secretary

Filing Exhibits & Attachments

2 documents

Other Documents

• EX-5.2 EX-5.2 11.2 KB
• EX-101 XBRL TAXONOMY EXTENSION SCHEMA WITH EMBEDDED LINKBASES DOCUMENT 40.5 KB