S&P 500 is at the bottom of a price channel. This does suggest a potentially low risk/high reward time to buy, though in light of other elements of price action, I'm actually bearish. Note the reversal candlestick pattern from last week (previous candle), and the inability to create a new high that it implies; when price reached that previous high, bears came right in and pushed it down.
I'm not trading this, but if I was, I'd be bearish with a down side target would be around 1,600, and my stop placed just above all-time highs. This would provide a very nice reward/risk setup.