Displayed above is a shoe that was commonly worn in a busy trading pit as the bottom had an additional inch added so the wearer could get a better sight line in the pit. The maximum which could be added was 3 inches to the bottom of the shoe per exchange rules and my guess is roughly 20% of those in a busy trading pit wore shoes such as these. The two articles below elaborate a bit more on the use of platform shoes as a competitive advantage.
Traders stand tall over hubbub with platform shoes
Brought Back to Earth At the Chicago Merc