Having named co-founder Jack Dorsey the permanent CEO on Monday, Twitter is about to make other big changes. According to Re/code, this includes cutting staff across the company -- starting next week.

Multiple Re/code sources said the engineering department could be the hardest hit, since it makes up about half of the total staff numbers and Twitter is “restructuring” to make it “leaner and more efficient.”

While it is unclear exactly how many staff will be let go, Re/code said “it will likely affect most, if not all, departments.”

A Twitter spokesperson said the company is “not commenting on rumor and speculation.” 

Last quarter, Twitter reported that it had about 4,200 people on staff, a number that has grown significantly from Q2 2013’s roughly 2,000 employees.

Twitter introduced Moments on Tuesday, allowing users to easily follow live events.