US stocks opened lower Monday after breaking a six-week slump with solid gains last week, with the jury still out over how strong the crucial Black Friday holiday sales went for retailers.
Also clouding the market were reports that talks over the fiscal cliff remained stuck on key issues, five weeks before the steep spending cuts and tax hikes are programmed to hit the economy.
An hour into trade (1530 GMT), the Dow Jones Industrial Average was down 67.78 points (0.52 percent) at 12,941.90.
The broad-market S&P 500 lost 6.75 (0.48 percent) at 1,402.40, while the Nasdaq Composite fell 6.22 (0.21 percent) to 2,960.63.
Retailers dependent on physical stores were mostly lower, with Walmart losing 0.8 percent, Costco 1.3 percent, and Target 1.9 percent.
The first weekend of the holiday sales period, kicked off with last week's Black Friday shopping bonanza, was strong, businesses said, but many were reported concerned that consumer spending might not be sustained over the next month.
Online retailers were higher, Amazon gaining 0.5 percent and eBay adding 2.3 percent, after Friday's online sales topped $1 billion for the first time.
Among the Dow blue chips, UnitedHealth Group gave up 1.6 percent and JPMorgan Chase fell 1.9 percent.
On the Nasdaq, Apple rose 1.0 percent, and Facebook zoomed 7.2 percent, while Google slipped 1.0 percent.
Bond prices rose. The 10-year US Treasury yield dropped to 1.65 percent from 1.69 percent Friday, and the 30-year fell to 2.79 percent from 2.83 percent.
Bond prices and yields move inversely.