The advent of 24 hour trading and more liquid pre- and post- markets has led to technical patterns that often complete after or before market hours. I think this is what happened last week — instead of happening during regular market hours the panic-sell off happened before trading started in the US. By the time US markets opened, key technical levels had already been tested and held and the markets stabilized. Then a combination of short covering, under-invested traders and momentum investors pushed the markets into overdrive. An analysis of the pre-market futures action shows that the markets tested the top of the support ranges from April.
I think this situation could make investors over-confident that the market can shrug off any bad event which could lead to a blow off top. In the short term, the markets can do anything as psychology and liquidity drive prices higher. But unless the Fed stops raising rates in August or September, which they have not given indication that they will do, I believe the markets could be in for an ugly Fall.