The week's 3 day pullback from the high of 2400 ended last night, when massive support came in at 2355. This drove the S&P up and out its downward channel breaking free at 2370. Heading for 2380 this is also a 50% retracement of its 2400/2355 range.
I would like to see S&P test 2390 to initiate a short, with a view that 2400 is the all-time high as I've mentioned before. If it breaks below 2350 before then, consider shorting at this key support level.
Long -term trend is up, but rapidly losing momentum so this is an aggressive long-term short entry (but a passive short-term short entry).