stock' in trade'
1. the requisites for carrying on a business, esp. goods kept on hand for sale in a store.
2. resources or abilities peculiar to an individual or group or employed for a specific purpose: A feeling for language should be part of the stock in trade of any writer. Also,stock'-in-trade'.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.