More unnerving conflicts around the globe have flared up, but as usual, U.S. equity investors have given it nary a yawn as they seem to have become pretty much numb to the steady stream of unwelcome news, particularly out of the Middle East. Now we enter the summer version of earnings season.

Stock investors entered the Fourth of July holiday on a high note, pushing the Dow Jones Industrials Index above 17,000 and the Wilshire 5000 Total Market Index above 21,000, and even pushing the S&P 500 to a smidge above the upper trend line of its long-standing bullish ascending channel that has been in place for nearly three years.

U.S. stocks just continue to cruise right along, although investors seem to be displaying a healthy level of caution, looking over their shoulders as they whistle past the graveyard and bet on ongoing improvement in corporate earnings and economic growth. Despite extremely overbought technical conditions and regional hot spots that may ultimately threaten global economic recovery, investors seem undeterred.

After its long-awaiting breakout of the 1900 level the other week, the S&P 500 gained another +1.3% last week alone, but this double-low progression as I call it -- i.e., on extremely low volume and with persistently low volatility -- is worrisome.