Joaquin Phoenix director Todd Phillips posted the cover of the script for the second film, which he co-wrote with Scott Silver, on his social media.
They also worked together on the first part.
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The second part has the working title Joker: Folie à Deux.
Folie à Deux is a French term for a form of induced psychosis in which two people experience the same mental disorder at the same time.
Phillips also posted a photo of Phoenix reading the script.