Sandler O'Neill and partners, an investment banking firm that specialises in financial services companies, has brought in Gregory Heher as a principal. Heher returns to the firm having left in 2009 to become head of coporate bond trading at Keefe, Bruyette & Woods. Heher will play a significant role in Sandler O'Neill's market making and principal transactions in the corporate bond markets. The firm has also hired Thomas Cullum to its fixed income group as a managing director with a focus on corporate bonds, as it continues to expand its fixed income platform.