Hallman was co-founder, with Norwegian broker Arne Naess, of the Naess Hallman brokerage, where he also served as chief executive and president. He worked at the firm from 1975 to 1990.

He is known for serving as one of the top S&P brokers to Canadian tanker owner Teekay.

Previously, he served in the US Army as a medic in Vietnam, where he lost both of his legs.

Hallman