Tech giants stall stock rally

Declines in tech giants including Apple, Amazon and Facebook dragged on equity benchmarks, helping erase the session’s gains on a day when quarterly rebalancing spurred volatile trading.

The S&P 500 Index was little changed Friday but still ended the week up after reaching a record high Thursday. Quadruple witching — when futures and options on indexes and individual stocks expire — and the largest revision to the Global Industry Classification Standard since 1999 may be behind the slide and the higher-than-average volumes.

“Bottom line, new highs are positive in the medium term, but I wouldn’t be chasing stocks at these levels and at a minimum, digestion of this rally shouldn’t surprise anyone,” Tom Essaye, a former Merrill Lynch trader who founded “The Sevens Report” market newsletter, wrote to clients. “Are things better than they were last week? Yes. Are they good enough to get the S&P 500 through 3,000 and above? No, not yet, at least in my opinion.”

Earlier, the bullish mood that characterized most of the week buoyed global equity markets. Stocks rallied in Europe and Asia, and the MSCI All-Country World Index was poised for a sevenmonth high. Treasury yields held above 3 percent. The dollar and commodities gained.