Pottruff & Smith Insurance Brokers Inc. was purchased by Cornerstone Insurance Brokers Ltd. on July 31, 2009. Cornerstone Insurance Brokers is a privately owned Canadian company. Re-established in 2007, Cornerstone has become one of the largest and most reputable multi-line insurance brokerages in Ontario, serving thousands of clients in all insurance categories - individuals, corporations, organizations, and provincial and national professional associations. Our national offices in Woodbridge/Vaughan, Aurora, Barrie, & Markham, Ontario; we have a service network spanning Canada.