This is a day on which we expect a turn in equity markets. This means a high point or a low point should be made on or very near the day in question and the prior trend determines which it will be. Today's drop (coming on top of Friday's weakness) means that a low point is probably being made hereabouts and we are looking for additional evidence to confirm this.
There are a few scattered intra-day signals developing, the most convincing of which is this 4-hourly bottom extension in NASDAQ futures:
This does not have the force of a daily-scale signal but it is probably an early sign that markets have 'fallen enough'. We would cover shorts in US and European equity indices now and try buying some S&P or Dow futures here.
There are no equivalent signals in Europe (yet) so we would wait before buying to go long there.