It's been quite a Santa Rally.

The stock market has gained about 10% this quarter. That's the best fourth-quarter performance since 2003 and the seventh-best in thirty years. Wall Street is cheering. The shops had a good Christmas. The economy may be perking up. Investors are feeling cheerful again, and strategists are predicting a happy new year for equities.

Two words: Bah, humbug.

I can't cheer this Santa Rally. Call me Scrooge. But I'll give you ten reasons why not -- and they don't even mention the dismal economy.

1. Shares may be more expensive than they're telling you. Wall Street says the market is still reasonably priced, at about 14 times forecast earnings. But two other measures tell a different story. The "Cyclically-Adjusted Price-to-Earnings Ratio" compares share prices to average earnings for the last ten years, not just for one year. And a measure called "Tobin's q" compares share prices to the cost of replacing company assets. These may seem off-the-wall measures, but for more than a century they have proven very good guides for long-term investors. Right now both say the market is about 75% above its average value: Not a bubble, but expensive. These don't mean the market will tank. But they do suggest your long-term returns from here may be modest.