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) ~~August~~May 2016, ~~2024~~2025

PIMCO Corporate & Income Opportunity ~~Fund~~

Fund

(Exact Name of Registrant as Specified in Its Charter)

Massachusetts

(State or Other Jurisdiction of Incorporation)

811-21238		~~466121513~~46-6121513
(Commission File Number)		(IRS Employer Identification No.)
1633 Broadway, New York, NY		10019
(Address of Principal Executive Offices)		(Zip Code)

(844) ~~337~~877-4626

(Registrant’s Telephone Number, Including Area Code)

Not Applicable

(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 ~~TradingSymbol~~Trading Symbol(s) Name of each ~~exchangeon~~exchange on which registered Common shares PTY New York Stock Exchange

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 ~~August~~May 15, ~~2024~~2025, ~~the~~PIMCO ~~Board~~Corporate & ~~approved~~Income ~~the~~Opportunity ~~removal of the~~ Fund’s ~~non-fundamental~~(NYSE: ~~investment~~PTY) ~~guideline for~~ (the ~~Fund~~ ~~to invest at least 25% of the~~ “Fund’s”) ~~total~~posted ~~assets~~an inamended ~~corporate debt obligations~~ and ~~other~~restated ~~corporate~~Section 19 Notice ~~income-producing~~to ~~securities~~its ~~and~~website ~~approved~~at ~~the~~www.pimco.com ~~addition~~that ofsets aforth ~~non-fundamental~~an ~~investment~~estimate ~~guideline~~of ~~for~~ the ~~Fund~~sources ~~to invest at least 50%~~ of the Fund’s ~~total~~distribution ~~assets~~payable ~~in corporate debt obligations and other corporate securities, effective September~~May 201, ~~2024.~~2025 ~~The supplement~~ to ~~the~~shareholders ~~Fund’s prospectus and statement~~ of ~~additional~~record ~~information disclosing~~on ~~this~~April 11, ~~change is attached hereto as Exhibit 99~~2025.1.

~~Item~~SIGNATURE ~~9.01 Financial Statements and Exhibits.~~

(d)		Exhibits
99.1		Supplement, dated August 20, 2024

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.

~~SIGNATURE~~PIMCO Corporate & Income Opportunity Fund By: /s/ Joshua D. Ratner Name: Joshua D. Ratner Title: President

~~Pursuant~~Date: ~~to the requirements of the Securities Exchange Act of 1934~~May 16, ~~the~~2025 ~~Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.~~

PIMCO Corporate & Income Opportunity Fund By: /s/ Ryan G. Leshaw Name: Ryan G. Leshaw Title: Chief Legal Officer and Secretary

Date: August 20, 2024

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