Goldman Sachs' top stock watcher David Kostin's latest update on the equities markets is sounding less than hugely bullish. He's looking at the fact that closely followed gauges of the business cycle, the ISM indexes, have been inching lower after hitting historically high levels. (After all it was the ISM services reading for April that sent stocks lower this morning.) Under a section of Wednesday's note entitled "Timing the Peak," Kostin writes:

Simply put, if you've been riding the materials and energy surge lately, it...