As a result of the financial crisis a large amount of financial companies decided to pay bonuses in restricted stock. Employee selling of restricted stock can have a large effect on stock prices and it makes sense to pay attention to lock up periods. Many employees do not want their entire financial future tied to their employer and look to diversify when their stock vests and the insider trading window opens. That might put pressure on financial stocks in the days following earnings, especially in January.
During my days at Goldman Sachs we were restricted from selling stock starting from a few weeks before the end of the quarter until 3 days after earnings. I am assuming this is the way it works at most financial firms. Additionally, restricted stock generally vests in year increments and restricted stock is likely given out during bonus season. Hence, the period after January earnings might see a lot of employee selling. While earnings from financial companies were far from stellar this might explain some of the recent weakness. I will try and remember this in a year from now.