Every now and then, 'they'll pull a surprise half day rally.
It's design to complete some orderbooks when no one is looking. Not the only reason of course,but it helps when volume is low to help market makers shift the market to their benefit easier.
That said,I'm not going to be going too frenzied after the 273 attempt tomorrow,price now 271.84.
I've seen the machines go bonkers into the half day close decently.