Stockbridge Partners is a subsidiary of Berkshire Partners which is a private equity shop. Stockbridge Partners was launched in 2007 and focuses on marketable securities. Robert J. Small has directed Stockbridge Investors since 2007 and he has been with Berkshire Partners since 1992. Previously he worked at Bain & Co. and Goldman Sachs. Stockbridge Partners has a long-term investment focus and invests only in a handful of stocks.