Aniston and Witherspoon are thought to have secured upward of US$1.25 million ($1.69m) per episode for The Untitled Morning Show Project; their huge salaries including fees for executive producing, according to the Hollywood Reporter.
On Monday, as Aniston celebrated her birthday in LA without her soon-to-be-ex husband of two years, Witherspoon shared a picture of the two of them back in 2000, when she guest-starred on two episodes of Friends as Rachel Green's youngest sister, Jill.
But while Aniston's new project sees her focusing on the New York media world, her preference for Los Angeles life is said to have proved a big part of her marriage breakdown.
Despite being born and raised in New York, she much prefers west coast life. Theroux, however, has a wide and varied friendship circle on the east coast.
Theroux, 46, and Aniston, 49, announced their split this week, following increased speculation about the state of their marriage.
In a joint statement, they said: "In an effort to reduce any further speculation, we have decided to announce our separation.
"This decision was mutual and lovingly made at the end of last year. We are two best friends who have decided to part ways as a couple, but look forward to continuing our cherished friendship."
Aniston and Theroux tied the knot in August 2015 in a secret ceremony at their Bel Air, California home.
