Yesterday’s cascade transformed the summer’s innocuous, oft-tedious shuffle into an impulsively bearish menace that seems unlikely to recede quickly.  Notice that the selloff exceeded three prior lows on the daily chart, two of them ‘external’. This is a powerful ‘impulsive’ start for bears, and it will likely become still moreso next week if there is only a modest bounce to end this one. Analytically speaking, we’ll be best able to judge the bear’s ferocity by whatever follow-through occurs after an upward correction. For now, though, we can use 1645.75 and 1629.00 as downside targets. The first number would represent at 0.618 retracement of the record-achieving rally begun on June 24; the second, a 50% retracement of same.