It's a red-number day for the stock market so far this morning, as nerves rubbed raw by Fed Chief Ben Bernanke's comments last week continue to roil markets. Financials are down overall, as is the Dow and the S&P 500, with Citigroup (C 0.11%) and Bank of America (BAC -0.96%) leading the big-bank plunge into the depths.

B of A, Citi, and JPMorgan Chase are all experiencing heavy trading right now, and all are falling. Even last week's favorite, Wells Fargo (WFC -1.46%) is heading downward, though trading volume is not excessive.

Choppy waters are sinking all ships
News coming out of the big bank sector isn't horrible, so it seems that the general market panic is likely at work here. Indeed, the news that Citi has secured permission to open offices in Iraq, considering the potential market that will likely emerge as the country heals, should be greeted in a positive manner. Yet, Citi is leading the dive, just ahead of B of A.

Similarly, Wells' drop is unexpected, since news late last week identifying the bank as the only one of the Big Four to have adequate capital to pass the stricter requirements currently being discussed caused its share price to jump considerably on Friday.

Despite myriad problems surrounding Bank of America -- including one that may cause a slew of new lawsuits -- today's downward spiral is probably due to the general nervousness pervading the market. Days like today stress the importance of the long-term view, which Foolish investors know paves the way to successful investing. Both stocks and entire markets can and will have bad days, and savvy investors know that time is the true test of a good investment, not one-day jumps and dives.