(Bloomberg) — Billionaire Ken Griffin is shutting down the Aptigon stock unit at his hedge fund Citadel a year after restructuring the group, according to a person with knowledge of the matter. Eric Felder, who has led Aptigon since last February, will leave the firm Thursday, said the person, who asked not to be named because the matter is private. Most of Aptigon’s money managers and their teams will join Citadel’s three remaining equity units: Citadel Global Equities, Surveyor Capital and Ashler Capital, said the person.