• by Sarah Mahoney  @mahoney_sarah, January 7, 2011

Best Buy says comparable-store sales fell 5% in December, with declines in entertainment software and TVs offsetting growth in mobile phones and appliances. And while the Minneapolis-based chain says the results were within the range of its expectations, the disappointing results are more evidence that tech sales weren't the Christmas present many retailers were hoping for.

In fact, the NPD Group reports that tech sales weakened across all channels. The Port Washington, N.Y. based market research company says that despite the heavily-promoted specials that started early in November, it estimates the nine-week holiday period will come in with some $14.9 billion in sales, 4% below the prior year.

"Record sales in 2009 across major categories such as notebook PCs and TVs, combined with a significant slowdown in the pace of price declines created a difficult headwind for the industry in 2010," the company says in its report. And while smartphones, e-readers and tablets were all bright spots, those gains couldn't make up for decreases. While TV sales actually gained, for example—with unit sales of flat-screen models climbing 5% and plasma sales jumping 32%--revenue for each type declined.