Summary Notice of Proposed Settlement of Derivative Actions

Compass Minerals (NYSE: CMP), a leading global provider of essential minerals, today released the following notice:

A U.S. District Court authorized this Notice. This is not a solicitation from a lawyer.

TO: ALL CURRENT RECORD HOLDERS AND BENEFICIAL OWNERS OF COMPASS MINERALS INTERNATIONAL, INC. ("COMPASS" OR THE "COMPANY") COMMON STOCK AS OF JULY 14, 2025 (THE "RECORD DATE").

IF YOU WERE A RECORD OR BENEFICIAL OWNER OF THE COMPANY'S COMMON STOCK AS OF THE RECORD DATE, PLEASE READ THIS NOTICE CAREFULLY AND IN ITS ENTIRETY, AS YOUR RIGHTS MAY BE AFFECTED BY PROCEEDINGS IN THE ABOVE-REFERENCED LITIGATION.

PLEASE TAKE NOTICE that the above-captioned consolidated derivative actions are being settled on the terms set forth in a Stipulation and Agreement of Settlement dated July 14, 2025 (the "Stipulation")1 of the above-captioned consolidated derivative actions, subject to the approval of the United States District Court for the District of Kansas (the "Court") pursuant to Rule 23.1 of the Federal Rules of Civil Procedure. Under the terms of the Stipulation, as part of the proposed Settlement, and in consideration of the associated releases set forth herein, Defendants shall cause the Board, within thirty (30) days after the Court enters an Order granting final approval of the Settlement, to adopt, implement, and maintain the corporate governance, oversight, and internal controls reforms set forth in Exhibit A to the Stipulation consistent with the terms and timing set forth therein (the "Reforms"). The Reforms, which are detailed more fully in the Stipulation and Long Form Notice, are intended to address the claims asserted in the Derivative Actions.

The Parties agree that: (i) the Settlement confers a substantial benefit upon Compass and its shareholders; (ii) the Settlement, and each of its terms, is in all respects fair, adequate, reasonable, and in the best interests of Compass and its shareholders; and (iii) Plaintiffs' Counsel are entitled to reasonable attorneys' fees and reimbursement of expenses, inclusive of Service Awards for the Plaintiffs, subject to the approval of the Court.

On October 14, 2025, at 1:30 p.m., the Court will hold the Settlement Hearing, either in person at Kansas City courthouse for the United States District Court for the District of Kansas, 500 State Avenue, Kansas City, Kansas 66101, or by telephone or videoconference (at the direction of the Court). At the Settlement Hearing, the Court will consider whether the Settlement is fair, reasonable, and adequate and thus should be finally approved and whether the above-captioned consolidated derivative action should be dismissed with prejudice pursuant to the Stipulation.

¹ Capitalized terms herein not otherwise defined are defined in the Stipulation. This Notice should be read in conjunction with, and is qualified in its entirety by reference to, the Stipulation and its Exhibits, which have been filed with the U.S. District Court for the District of Kansas.

The Court also will rule upon Plaintiffs' Counsel's request for approval of the agreed-upon attorneys' fees and reimbursement of expenses and Plaintiffs' Service Awards.

Any Current Compass Stockholder may, but is not required to, appear in person at the Settlement Hearing. If you want to be heard at the Settlement Hearing in opposition to the Settlement, Plaintiffs' Counsel's request for approval of attorneys' fees and reimbursement of expenses, or the Service Awards, then you must first comply with the following procedures for objecting.

Any objections to the proposed Settlement or Plaintiffs' Counsel's applications for the Fee and Expense Amount of $1,400,000, to be paid by the Individual Defendants' Insurers, and reasonable Service Awards of up to $2,000 for each of the two Plaintiffs to be paid from the Fee and Expense Amount, must be presented in writing and must contain the following information:

1. Notice of intent to appear at the Settlement Hearing;
2. Your name, legal address, and telephone number;
3. Proof of being a Current Compass Stockholder as of the Record Date and representation that you will continue to own Compass common stock as of the date of the Settlement Hearing;
4. The date(s) at which you acquired your Compass shares and the number of Compass shares held;
5. A detailed statement of your specific position with respect to the matters to be heard at the Settlement Hearing, including a statement of each objection being made; and
6. The grounds for each objection or the reasons for your desire to appear and be heard.

Any counsel retained by a purported objector for the purpose of asserting an objection must make a notice of appearance on the Court at least fourteen (14) days before the Settlement Hearing. The Court will not consider any objection that does not substantially comply with these requirements.

Any written objections must be filed with the Court and sent by hand or by first-class mail, postage prepaid to Plaintiffs' Counsel no later than fourteen (14) days before the Settlement Hearing at the following address:

The Court will not consider any objection that is not timely filed with the Court and delivered to Plaintiffs' Counsel.

Any person or entity who fails to object or otherwise request to be heard in the manner prescribed above will be deemed to have waived the right to object to any aspect of the Settlement or otherwise request to be heard (including the right to appeal) and will be forever barred from raising such objection or request to be heard in this or any other action or proceeding, but shall otherwise be bound by the Judgment to be entered and the releases to be given.

This Notice summarizes the Parties' Stipulation. It is not a complete statement of the events of the Derivative Actions or the Stipulation. You may inspect the Stipulation and other papers at
https://investors.compassminerals.com/investors-relations/investor-resources/market-data/default.aspx .

PLEASE DO NOT CALL, WRITE, OR OTHERWISE DIRECT QUESTIONS TO EITHER THE COURT OR THE CLERK'S OFFICE. Any questions you have about matters in this Notice should be directed by telephone or in writing to Plaintiffs' Counsel at the address set forth above.

Dated: Aug. 28, 2025, BY ORDER OF THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF KANSAS

Use of Forward-Looking Statements
This press release contains "forward-looking statements" within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995, including, without limitation, those regarding: (i) the Stipulation resolving the derivative actions; (ii) the ability to secure final approval of the proposed Settlement and to satisfy all conditions of the proposed Settlement; and (iii) other statements that are not historical facts, constitute forward looking statements. These forward-looking statements involve risks and uncertainties that can cause actual results to differ materially from those in such forward-looking statements. Forward-looking statements are subject to a number of risks and uncertainties, many of which involve factors or circumstances that are beyond our control, including, without limitation, risks and uncertainties related to: (a) the Stipulation not having the expected impact, including resolving the derivative actions; (b) the proposed settlement requiring more activity or expense than expected; (c) the defendants' ability to overcome any objections or appeals regarding the proposed settlement; and (d) satisfactory resolution of any future litigation or other disagreements with others. Further information on potential factors that could cause actual results to differ materially from those in the forward-looking statements are contained in the Company's filings and periodic reports filed with the Securities and Exchange Commission under the heading "Risk Factors" and elsewhere in such filings and reports, including our most recent quarterly report on Form 10-Q for the quarter ended June 30, 2025, and future filings and reports by the Company. Undue reliance should not be placed on forward-looking statements, which speak only as of the date they are made, and the facts and assumptions underlying the forward-looking statements may change. Except as required by law, the Company disclaims any obligation to update these forward-looking statements to reflect future information, events or circumstances.

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