Analysts offered mixed signals on the S&P 500’s near-term outlook, making a Santa rally uncertain, pointing to potential volatility, amid atypical seasonality and rising bearish options sentiment.

As of market close on Dec. 24, the markets had notched a straight week of gains. Headlines were hyping a "Santa Claus rally," and analysts were getting ready to bust out the milk and cookies early.

I believe in Santa Claus. I make that declaration every year before Christmas, and every year, without fail, I’m mocked (mainly by family members) or labeled “cheesy” by online scolds and various ...