Pit was likely based on the very successful game, Gavitt's Stock Exchange, invented in 1903 by Harry E. Gavitt of Topeka, Kansas.
The cards consist of nine of each commodity, all various grains (wheat, flax etc.), and two special cards, a bull and a bear. The winner is the first player to gather nine matching cards. The game uses as many commodities as there are players. The cards are shuffled and dealt equally between the players, the players are allowed a few momets to arrange their cards then the dealer starts the game.
There are no turns and no order of play, the players make others aware of the cards they wish to dispose of by repeatedly yelling the number (up to four) but not the type, but all the offered cards must be identical (or include a bull and/or bear). Someone wishing to trade an equal number of cards will accept the bid and the two players will exchange cards facedown, all bids and exchanges are conducted simultaneously by all players. When a player has nine matching cards they yell 'corner' and gain points matching the value of their commodity (40 to 100 points) and the game begins again. The bull card is wild and can be used to complete any set or double the value of a nine card set. If a trading session ends and the bull or bear cards are in the hands of losing players they are each worth minus 20 points.
The game ends when an agreed score has been reached, usually 500 points.