For all the talk of a rotation out of technology and into value stocks, it's worth noting that many tech stocks did just fine last week. The S&P 500 technology index fell 2.65 per cent in the first two days of last week but 56 of its 72 component stocks actually advanced, notes the Leuthold Group's Jim Paulsen. The discrepancy is explained by the rout in a handful of high-flying tech stocks with the NYSE Fang+ index falling 5.6 per cent. It's not so much a tech sell-off, says Paulsen, but a Fang (Facebook, Amazon, Netflix and Google) sell-off.

The Fangs rebounded somewhat on Wednesday, so talk of an ongoing rotation may be premature. Still, investors have piled into Fang-like stocks this year. Going long in the technology sector has become the most crowded trade of all time, according to recent fund-manager surveys, meaning it may be time for the high-flyers to finally take a breather.