In Q3 2013, the top 13 investment banks experienced a 13% decline in revenue compared to Q3 2012, largely due to decreased FICC revenues which were slightly offset by strong performance in equity derivatives and prime services. While banks continued to reduce headcounts, restructuring efforts were emphasized over further cuts; J.P. Morgan and Citi gained market share, whereas Goldman Sachs faced challenges. Despite overall revenue pressures, certain sectors like DCM and M&A saw notable growth, indicating a mixed performance across capital markets.