Low-priced financial stocks dominating trading volume

August is known as a quiet month for the stock market, as many institutional investors and traders take advantage of the waning summer to go on vacation. Trading volume dries up, and some large price swings can be attributed to the lack of liquidity, but this news about the concentrated nature of trading is truly odd.

According to Reuters, four beaten-up financial companies -- Bank of America (BAC), Citigroup (C), Fannie Mae (FNM), and Freddie Mac (FRE) -- have accounted for upwards of 40 percent of the trading volume on the New York Stock Exchange to begin this week.