Option traders swarmed CBS Corporation (NYSE:CBS - 40.95) on Thursday, with many speculators placing last-minute bullish bets. By the time the dust settled, the media conglomerate saw roughly 92,000 call contracts change hands -- about 11 times its average single-session call volume, and about three times the number of put options exchanged.

More than half of the volume transpired at the stock's January 2013 42-strike call, which saw more than 48,000 contracts cross the tape. The majority of the calls traded at the ask price, and call open interest at the soon-to-expire strike skyrocketed overnight, underscoring our theory of newly bought bullish bets.

By purchasing the calls at a volume-weighted average price (VWAP) of $0.20, the buyers will profit if CBS extends yesterday's rally and topples the $42.20 level (strike plus VWAP) by today's closing bell. However, even if the shares take a breather, the most the traders can lose is the premium paid for the options.

From a broader sentiment standpoint, options players were waxing optimistic on CBS even before yesterday's spinoff-induced surge. During the past two weeks, traders have bought to open almost four CBS calls for every put on the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX). In fact, the equity's 10-day call/put volume ratio of 3.84 ranks in the 65th percentile of its annual range, pointing to a healthier-than-usual appetite for bullish bets of late.

As a result, the stock's Schaeffer's put/call open interest ratio (SOIR) has dropped to 0.34, indicating that calls nearly triple puts among options with a shelf-life of three months or less. Plus, this ratio sits just 1 percentage point from a 12-month low, implying that near-term options players have rarely been more call-skewed during the past year.

After jumping nearly 8% yesterday, and touching a decade-plus high of $42.55, the shares of CBS are pointed fractionally higher in pre-market action. However, the equity's Relative Strength Index (RSI) now sits at 71 -- in overbought territory, suggesting a pullback could be in the short-term cards.