Exhibit 99.1

MATERIAL FACT (“HECHO ESENCIAL”)

Celulosa Arauco y Constitución S.A.

Santiago (Chile), July 23^th, 2024

Commission for the Financial Market

(Comisión para el Mercado Financiero)

PRESENT

To whom it may concern:

The undersigned, on behalf of the corporation (sociedad anónima) named Celulosa Arauco y Constitución S.A. (the “Company” or “Arauco”), domiciled in the Metropolitan Region of Chile, at Avenida El Golf No. 150, 14^th Floor, commune of Las Condes, Chilean Taxpayer Identification No. 93,458,000-1, and being duly entitled for these purposes, hereby reports the following material information concerning the Company and its businesses, pursuant to article 9 and the second paragraph of article 10, both of Law No. 18,045, and Regulation of General Application (Norma de Caracter General) No. 30, issued by the Commission for the Financial Market (the “Commission”).

In Arauco's Board of Directors meeting held today, July 23, 2024, it was agreed to amend the Manual for the Management of Information of Interest to the Market (Manual de Manejo de Información de Interés para el Mercado), the new version of which will be sent to this Commission and published on the Company's website (www.arauco.com ).

Very truly yours,

CELULOSA ARAUCO Y CONSTITUCION S.A.

Cristián Infante Bilbao

Chief Executive Officer

c.c.

- Santiago Stock Exchange. La Bolsa No. 64, Santiago

- Chilean Electronic Exchange. Huérfanos 770, 14^th Floor, Santiago

- Representative of the Bondholders (Banco Santander). Bandera 140, Santiago