I do agree with you that the market does seem shaky and looking for any reason to sell off. The last 45 min and the after market selling seemed to me to be an effort to reduce overnight risk on long stock positions by hedging them with short positions in
SP 500, Nasdaq 100, and Russell 2000 futures
June SP 500 futures are currently approx. 11.30 below fair value.
If Asia does sell off, tomorrows opening will be brutal for the bulls.
On the other hand if Asia rallies strongly, we will have a nice snap back rally on the open.