Dividend hikes, like Wal-Mart's, aren't always great news for investors

As if beating expectations by posting a 5.1 percent growth in same-store sales wasn't enough, Wal-Mart (WMT) also announced yesterday that it's increasing its annual dividend by 15 percent, to $1.09 a share. That helped boost the world's largest retailer's shares, which rose 2.6 percent on a day the Dow Jones Industrial Average fell another 280 points.

It's certainly unusual for any company to raise its dividend during tough economic times like these. Troubled Citigroup (C) stopped paying a dividend, General Electric (GE) cut its dividend payout, and Google (GOOG) said it is letting its cash "pile up" with no intention of starting to pay a dividend. But -- surprise, surprise -- Wal-Mart isn't actually alone in raising its dividend.