With Pfizer Inc. (NYSE:PFE - 25.35) advancing to a new annual high on positive news for its Prevenar 13 vaccine, some speculators are taking the opportunity to try and call a top. Put volume is currently running at three times the average pace, with roughly 30,000 contracts changing hands.

The most-active option is the out-of-the-money October 23 put, where almost 22,000 contracts have traded on existing open interest of 16,000. A block of 21,510 contracts hit the tape in one fell swoop, trading for the ask price of $0.02 per contract. Despite the low premium, the block still cost more than $43,000 for the aggressive short-term bet.

For this put to be profitable, the stock needs to dip below $22.98 (strike price minus debit paid) by October options expiration in about two weeks. That's a decline of more than 9% into territory the stock hasn't visited since mid-July. Earnings aren't expected until the end of the month, so the bears don't have the potential for an earnings miss, barring any unscheduled guidance news.

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