13G Filing: Avenue Capital Management II, L.P. and Magnachip Semiconductor Corp (MX)

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SCHEDULE 13G/A

This Amendment No. 5 (this Amendment) to the Schedule 13G filed on February 9, 2012, as amended by Amendment No. 1,
filed on February 1, 2013, as subsequently amended by Amendment No. 2, filed on February 28, 2014, as subsequently amended by Amendment No. 3, filed on February 13, 2015, as subsequently amended by Amendment No. 4,
filed on February 12, 2016 (the Schedule 13G) is being filed on behalf of Avenue Partners, LLC (Avenue Partners), Avenue Capital Management II, L.P. (Avenue Capital Management), Avenue Capital Management
II GenPar, LLC (Avenue Capital Management GenPar) and Marc Lasry relating to shares of Common Stock, par value $0.01 per share (the Common Stock), of MagnaChip Semiconductor Corporation, a Delaware corporation (the
Issuer).

Item 4 of the Schedule 13G is amended and restated in its entirety to read as follows.

Item 4

Ownership.

See cover pages Items 5-11.

As of August 15, 2017, Avenue Capital Management, Avenue Capital Management GenPar and Marc Lasry beneficially own no shares of Common
Stock of the Issuer.

Item 5

Ownership of Five Percent or Less of a Class.

If this statement is being filed to
report the fact that, as of the date hereof, the reporting person(s) has/have ceased to be the beneficial owner of more than five percent (5%) of the class of securities, check the following box ☒.

Item 6

Ownership of More Than Five Percent on Behalf of Another Person.

Not applicable.

Item 7

Identification and Classification of the Subsidiary which Acquired the Security Being Reported On by the Parent Holding Company.

Not applicable.

Item 8

Identification and Classification of Members of the Group.

Not applicable.

Item 9

Notice of Dissolution of Group.

Not applicable.

Item 10

Certification.

By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a
participant in any transaction having that purpose or effect.