Adams Express Company Couriers. A delivery company since the 1830s, in 1854 it was re-organised as Adams Express. Following a robbery, the company employed Allan Pinkerton who went on to found Pinkertons National Detective Agency. The company used to own a large share of Amex and some Railways. In 1929 the company got out of the delivery trade and became a closed-end fund quoted on the Wall Street Exchange where it remains to this day.It has a market cap of about $1 billion (exchange symbol: New York-ADX).