13D Filing: M&G Investment Management Ltd and Methanex Corp (NASDAQ:MEOH)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington,
D.C. 20549

SCHEDULE 13D

Under the
Securities Exchange Act of 1934

(Amendment No.         )*

Methanex Corporation

(Name of Issuer)

Common Stock

(Title of Class of Securities)

59151K108

(CUSIP Number)

800 Waterfront Centre, 200 Burrard
Street, Vancouver, BC, V6C 3M1, Canada

(Name,
Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

15 March 2017

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing
this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ☒

Note: Schedules filed in paper format shall include a signed original and five copies of the
schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

^* The remainder of this cover page shall be filled out for a reporting persons initial filing
on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be filed for the purpose of Section 18 of the
Securities Exchange Act of 1934 (Act) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).