FedEx expects to ship 280 million packages between Thanksgiving and Christmas, up 13 percent from a year ago, thanks to consumers' growing fondness for shopping online. FedEx moves a bulk of its cheaper, lighter weight shipments from online and catalog retailers through its SmartPost service, a partnership with the U.S. Postal Service. The forecast comes against a background of lackluster growth in the global economy. The Memphis, Tenn., expects Dec. 10 to be its busiest day with 19 million shipments, up 10 percent from 2011. Rival UPS, based in Atlanta, hasn't yet released a holiday forecast. The National Retail Federation expects holiday sales to increase 4.1 percent. That would be the smallest increase since 2009. Research firm eMarketer forecasts online holiday sales will grow 16.8 percent, excluding travel purchases.