Monthly options expiry on $SPY showing call-buying pressure concentrated in the $771-$779 strike zone. That's institutional flow setting up for a bounce or defending a floor — when dealers sell those calls, they hedge by buying futures, which creates mechanical bid pressure. Watch gamma pin dynamics into Friday's close; if we hold above $771, those short calls stay in play and dealers stay long delta. Break below and the hedging unwinds fast. Classic OPEX setup where the strike cluster becomes the battleground.