It's the final countdown for retailers who have done their best to whet U.S. consumers' appetites for Christmas shopping deals, and the stores may show whether they have made the best of a truncated shopping season.

ShopperTrak data will provide a snapshot of the weekend's results on Monday, with a few more indicators expected later in the week. The last few days before Christmas could be particularly tricky for Target, which is dealing with the aftermath of a massive cyber-security breach.

There could also be signs of movement on the adoption of Obamacare after Monday's "deadline" for Americans to sign up for insurance plans created under President Obama's star-crossed healthcare law. Like many things about the law, the deadline is proving more malleable than it initially appeared. But the week still could bring some indication of enrollment numbers and whether they continue to lag far beyond the administration's initial hopes.

Markets are likely to downshift into a lower gear, with the Christmas holiday keeping liquidity to a premium and as investors avoid making dramatic moves that might hurt what's been a profitable year with 27 percent price appreciation in the S&P 500. Recent curve-flattening trades, where investors have been buying longer-dated bonds and selling bonds in the five-year maturity, may continue as the market believes there are greater chances of interest rate increases sooner than later. The dollar is likely to hang onto recent gains, though the dollar index has not broken out of an overall weakening trend.

Markets are closed for holiday observance in Germany and Italy on Tuesday and in many countries on Wednesday, including Canada, Hong Kong, the U.K. and the United States.

America's rip-roaring economic growth in the third quarter was powered by stronger-than-expected business investment, consumer spending and inventory accumulation. Data this week could give signs that some of this economic momentum carried over into the fourth quarter. The final print for December of the Thomson Reuters/University of Michigan consumer sentiment index, due on Monday, is expected to rise to its highest level in five months. A report due on Tuesday could show new orders of durable goods in October swung back from a contraction registered the prior month.

The Food and Drug Administration is due to decide by Friday whether to authorize U.S. marketing of Sanofi's multiple sclerosis treatment Lemtrada, which has been in development for over 20 years. One of Sanofi's two new drugs for MS, an autoimmune disease that attacks the central nervous system and affects more than two million people worldwide, Lemtrada was approved by European regulators in September. The drug's prospects were center-stage in Sanofi's $20.1 billion takeover of Genzyme in 2011.