The S&P 500 Financials Index lost 4.8% in August, compared to a 1.6% drop for the S&P 500 as a whole. Fifty-one of the 68 financial companies in the index ended the month with negative returns.
Unum Group's stock lost 20.5% last month, making the insurer the worst-performing company in the index. Fellow insurer Prudential Financial Inc. had the second-worst performance with a 20.0% loss, followed by Franklin Resources Inc.'s 19.5% slide.
Meanwhile, MarketAxess Holdings Inc. and CME Group Inc. led the index with gains of 18.1% and 11.8%, respectively. Two other financial exchanges, Cboe Global Markets Inc. and Nasdaq Inc., were also among the top 10 companies by performance in the index last month.

