C07171-2026

SECURITIES AND EXCHANGE COMMISSIONSEC FORM 17-C

CURRENT REPORT UNDER SECTION 17
OF THE SECURITIES REGULATION CODE
AND SRC RULE 17.2(c) THEREUNDER

1. Date of Report (Date of earliest event reported)
Oct 1, 2026
2. SEC Identification Number
0000091447
3. BIR Tax Identification No.
0001903240000
4. Exact name of issuer as specified in its charter
Semirara Mining and Power Corporation
5. Province, country or other jurisdiction of incorporation
Philippines
6. Industry Classification Code(SEC Use Only)
7. Address of principal office
2/F DMCI Plaza, 2281 Don Chino Roces Avenue, Makati City Postal Code 1231
8. Issuer's telephone number, including area code
8246-2280/8246-2238
9. Former name or former address, if changed since last report
N/A
10. Securities registered pursuant to Sections 8 and 12 of the SRC or Sections 4 and 8 of the RSA
Title of Each Class Number of Shares of Common Stock Outstanding and Amount of Debt Outstanding
Common 4,250,547,620
11. Indicate the item numbers reported herein
9

The Exchange does not warrant and holds no responsibility for the veracity of the facts and representations contained in all corporate disclosures, including financial reports. All data contained herein are prepared and submitted by the disclosing party to the Exchange, and are disseminated solely for purposes of information. Any questions on the data contained herein should be addressed directly to the Corporate Information Officer of the disclosing party.

Semirara Mining and Power CorporationSCC

PSE Disclosure Form 4-30 - Material Information/Transactions References: SRC Rule 17 (SEC Form 17-C) and
Sections 4.1 and 4.4 of the Revised Disclosure Rules

Subject of the Disclosure

Update on Mine Operations and Redundancy Program
Background/Description of the Disclosure

We wish to inform the Exchange and the investing public of recent developments affecting the coal mining operations of Semirara Mining and Power Corporation (“SMPC” or the “Company”) at its Mine Site on Semirara Island, Caluya, Antique.

1. Seawater Seepage at Acacia Mine. The Company has been managing seawater seepage at its Acacia Mine. Despite ongoing remedial measures, the seepage discharge rate has increased to approximately 30,000 cubic meters per hour (m³/hr), with more than half directed to the Acacia pit bottom. This volume exceeds the Company’s current pumping capacity. On 20 September 2026, dumped and in-situ materials from North Block 1 Dam 2 collapsed, redirecting significant runoff toward the Acacia pit.

2. Remedial Measures. SMPC has commenced construction of a new cut-off wall north of the collapsed area to seal off seepage pathways and reduce the volume of runoff entering Acacia. Stripping operations in Acacia West Block 2 have been temporarily suspended to prioritize remedial measures, except for excavations necessary to support the Acacia-Molave barricade, mudstone backfilling, and mining of exposed coal seams. The Company continues to coordinate with the Department of Energy (“DOE”) on the technical response and long-term solutions.

3. Suspension of Acacia Stripping Operations. In light of the current seepage conditions, the Company has partially suspending stripping operations at Acacia for an uncertain period while pursuing remedial measures. Coal extraction continues from the Company’s remaining accessible pits. The Company will report revised production estimates as they become available.

4. Manpower Alignment. The Board of Directors in its meeting held today, October 1, 2026 approved a Supplemental 2026 Operations and Manpower Alignment Program and a companion Supplemental Mine Site Redundancy Program to address the manpower alignment necessitated by the Acacia mine stripping operation suspension.

5. Continuing Operations. SMPC continues to operate under Coal Operating Contract No. 5 with the DOE. Environmental, rehabilitation, safety, and community obligations — including the Acacia pit management and remediation program — are preserved. The Company remains committed to responsible mine operations and to the sustained development of its host and neighboring communities.

The Company shall keep the Exchange and the investing public informed of any material developments
Other Relevant Information

Attached is SEC Form 17-C.
Filed on behalf by:
Name Sonny Sibug
Designation Legal and Admninistrative Officer