US markets closed lower on Monday amid a continuing slide in technology stocks.
Gains for energy and industrial companies failed to offset the losses, which spread to other sectors.
The Dow Jones fell 36.3 points, or 0.2%, to 21,235.6 points, while the wider S&P 500 index dropped 2.3 points, or 0.1%, to 2,429.3.
The tech-focused Nasdaq index fell 32.4 points, or 0.5%, to 6,175.4.
Apple fell 2.5% after Mizuho Securities cut its rating on the tech giant to "neutral" from "buy" - its second downgrade in a week.
Netflix dropped 4.2%, Amazon shed 1.4%, Alphabet dropped 0.9% and Facebook was down 0.8%.
Tech stocks have risen rapidly since April following strong results for many firms.
Neil Wilson at ETX Capital said the recent surge had left investors wondering "if there is anything left in the tank".
"It looks like it's just a pause that allows for some profit-taking before another push higher, but it certainly has the potential to rattle markets if it continues," he said.
Shares in McDonald's fell 2% after the fast food chain said it planned to hire 250,000 people, aiming in particular at younger workers via Snapchat.
Among the risers, General Electric added 3.6% after it said Jeff Immelt was retiring from the US industrial giant after 16 years as chairman and chief executive.
He will depart on 31 December and be replaced by John Flannery, the head of GE's healthcare division.