Certificates are still perfectly valid, but most stock is “dematerialised” and held at a central securities depository, like DTC - https://en.m.wikipedia.org/wi

Certificates are still perfectly valid, but most stock is “dematerialised” and held at a central securities depository, like DTC - https://en.m.wikipedia.org/wiki/Depository_Trust_Company https://en.m.wikipedia.org/wiki/Depository_Trust_Company This allows transfer by “book entry” rather than mailing the physical documents - much like an electronic bank transfer.