Bullish options traders rang the register with hefty profits in pharma firm Tesaro Inc. (TSRO) on Wednesday.

On September 17, Investitute's proprietary programs flagged the purchase of 4,500 October $30 calls for $5.37 to $6.50 with shares at $34.93. This was clearly a new position, as open interest in the strike was a mere 43 contracts before the trade occurred.

The shares of TSRO at the time were rebounding from a slide lower and appearing to gain favor once more. These investors could have purchased those in-the-money calls to create a synthetically long position in the underlying common stock.

Those October $30 calls sold for $13.60 by Wednesday, October 17, more than double their purchase prices, and much deeper in-the-money than they were at their initiation. The stock rose 25.39% in the same time period, a big move but nowhere near that of its options. It was the second winning trade in Tesaro posted on Investitute in a little more than a month.

Long calls lock in the price where investors can buy a stock, letting them position for a rally at limited cost with the potential for significant leverage. They carry less risk than owning shares because the most that can be lost is the price of the options no matter how far the stock might fall.

Tesaro was up 2.05% to close at $44.29 Wednesday. The biopharmaceutical oncology firm is scheduled to present data from six abstracts at the European Society for Medical Oncology Congress held on October 19-23 in Munich.