I think it's a combination of three factors. First, central banks are propping up the markets and have stated they will do whatever it takes. That gives invest

I think it's a combination of three factors. First, central banks are propping up the markets and have stated they will do whatever it takes. That gives investors confidence that they wont face excessive risk. Second, unemployment is not yet affecting that much the sort of people who invest in stocks, upper-middle class white collar workers. Third, investors are still optimistic that this will be a temporary setback and things will return to normal fairly quickly.