The second quarter of 2017 saw an increase in the number of SEC-client auditor changes among the major firms from last quarter. Overall, there were 58 new engagements this quarter, compared to 48 in Q1. Deloitte was the leader (for the second quarter in a row) with 15 gains and 6 losses, for a net of 9 new clients. RSM US, Crowe Horwath, Marcum, and Grant Thornton also had net increases in new clients this quarter.
This article from Audit Analytics charts the gains and losses of the major firms, the auditor changes by the size of the companies gained or lost, and a sample of the largest wins and losses for accelerated filers and smaller reporting companies.