[0] https://www.reuters.com/article/us-dell-ipo-idUSKCN1OR14E
[1] https://www.wsj.com/articles/dell-returns-to-public-equity-m...
[2] https://www.theverge.com/2018/12/28/18159305/dell-stock-mark...
Pedantic nit: not quite an IPO (Initial Public Offering) in its true sense since the original ARM Holdings was already a public limited company (PLC) before Softbank bought it from its shareholders in 2016. The trading entity and group parent is Arm Ltd, a private limited company formed in 1990 [0].
There is however a currently dormant Arm Holdings Ltd [1] incorporated in 2018 which may be converted to a public company so it would be the first time this legal entity has been publicly listed.
[0] https://find-and-update.company-information.service.gov.uk/c...
[1] https://find-and-update.company-information.service.gov.uk/c...