Form 485BXT RUSSELL INVESTMENT CO

Filed Pursuant to Rule 485(b)

Registration No. 002-71299

811-03153

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

and

REGISTRATION STATEMENT

UNDER

RUSSELL INVESTMENT COMPANY

(Exact Name of Registrant as Specified in Charter)

Registrant’s Telephone Number, including area code: 206-505-7877

(Name and Address of Agent for Service)

Approximate date of commencement of proposed public offering: As soon as practical after the effective date of the Registration Statement.

It is proposed that this filing will become effective (check appropriate box)

If appropriate, check the following box:

PART A, PART B and PART C

The Registrant hereby incorporates in its entirety each of Part A, Part B and Part C of Post-Effective Amendment No. 271 to Registration Nos. 002-71299 and 811-03153 into, and hereby designates each such Part as constituting in its entirety Part A, Part B and Part C, respectively, of Post-Effective Amendment No. 272 to Registration Nos. 002-71299 and 811-03153. This Post-Effective Amendment No. 272 is being filed to extend the effective date of previously filed Post-Effective Amendment No. 271. The Registrant’s updated Prospectus, Statement of Additional Information and Other Information will be filed pursuant to 485(b) on or before March 1, 2026.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant, Russell Investment Company, certifies that it meets all of the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) of the Securities Act of 1933. The Registrant has duly caused this Post-Effective Amendment No. 272 to its Registration Statement to be signed on its behalf by the undersigned thereto duly authorized, in the City of Seattle, and State of Washington, on this 5th day of February, 2026.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities indicated on February 5, 2026.