We all know that this Christmas is going to be particularly tough on retailers. Wal-Mart (NYSE: WMT), Target (NYSE: TGT), Sears (NASDAQ: SHLD), and Best Buy (NYSE: BBY), as well as hipper competitors Abercrombie & Fitch (NYSE: ANF) and Gap (NYSE: GPS), will be fighting it out at the mall Mad-Max style the next several weeks.

It's not going to be pretty. With comps and cash flows on the line, these chains will be looking to extract as much discretionary money from consumer wallets as is heavenly possible. But there's a troubling sign with respect to a popular gift option this year.

Gift cards have been soaring in popularity over the years. Not only do they make great presents, but retailers love them because they represent a little insurance policy: if the Christmas quarter isn't as strong as a retailer would like, then redemption of gift cards will theoretically help the bottom line in the next quarter. The card purchases do not get recorded as a sale until they are redeemed. So it's like a squirrel putting food away for the long, cold winter.

Unfortunately, we have some bad news on this front: gift-card sales are expected to be down 6% this season. That's not what retail investors want to hear. It's just another reason for traders to short this sector.