QuickLinks -- Click here to rapidly navigate through this document

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, DC 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)    May 26, 2005

Citigroup Inc.
(Exact name of registrant as specified in its charter)

Delaware (State or other jurisdiction of incorporation)	1-9924 (Commission File Number)	52-1568099 (IRS Employer Identification No.)
399 Park Avenue, New York, New York 10043 (Address of principal executive offices) (Zip Code)
(212) 559-1000 (Registrant's telephone number, including area code)

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:

o

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

o

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

o

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

o

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

Citigroup Inc.
Current Report on Form 8-K

Item 7.01    Regulation FD Disclosure.

        On May 26, 2005, Citigroup Inc. will hold an investor presentation to review its Corporate and Investment Banking Business.

        Exhibit 99.1 is a copy of certain presentation materials used in connection with the investor presentation. This information is being furnished pursuant to Item 7.01 of this Current Report on Form 8-K, and the information contained in Exhibit 99.1 shall not be deemed to be "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities under Section 18. Furthermore, the information contained in Exhibit 99.1 shall not be deemed to be incorporated by reference into the filings of Citigroup Inc. under the Securities Act of 1933, as amended.

Item 9.01    Financial Statements and Exhibits.

(c)

Exhibits

Exhibit Number

        99.1    Certain presentation materials for investor presentation.

2

SIGNATURE

        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.

Dated: May 26, 2005	CITIGROUP INC.
	By:	/s/  JOHN C. GERSPACH
	Name:	John C. Gerspach
	Title:	Controller and Chief Accounting Officer

3

EXHIBIT INDEX

Exhibit Number
99.1	Certain presentation materials for investor presentation.

4

QuickLinks

Citigroup Inc. Current Report on Form 8-K

Item 7.01 Regulation FD Disclosure.
Item 9.01 Financial Statements and Exhibits.

SIGNATURE
EXHIBIT INDEX