From Seeking Alpha:
If in fact the markets continue to slide, thereby adding to losses on an S&P 500 index that are already 7.5% off 52-week highs, then last week will prove to be very important as a lesson for what to expect. In the year 2000, it was overvalued technology stocks that got hit first and hardest. In 2008, financial stocks led the pack, which then carried over to companies affected by the financial crisis (ie everything). Then, in 2011, it was like a mini-2008, investors sold stocks like financials and auto makers that were the biggest losers just three years prior.