The man was left fighting for his life in hospital after he was “viciously attacked” at Oxford Circus Tube station.
Police were called to reports of a serious assault on the southbound Bakerloo line platform three at about 11.15am on Sunday, November 5.
Following a police appeal for information, nine people have been arrested.
Officers have also CCTV images of six people they want to speak to after the incident.
Two 19-year-old women, two 19-year-old men, a 17-year-old girl and a 23-year-old man, all from the London area, were arrested on Wednesday.
A further three females, aged 16, 17 and 19, all from the London area were arrested on Friday and are currently in police custody.
If you have any information please contact British Transport Police on 0800 40 50 40 or text 61016 citing 195 of 05/11/17.