It took just two weeks for bullish options traders to double their money in the Wisdom Tree Japan Hedged Equity Fund (DXJ) - Get Report .

On September 20, Investitute's proprietary programs flagged the purchase of 20,000 November $59 calls for $0.60 as part of a bullish roll with shares at $57.20. This was clearly a new position, as open interest in the strike was only 427 contracts before the trade occurred.

Large-cap and mega-cap equities on US exchanges were just starting to look in favor at the time, and these investors may have believed that the shift to the larger, more industrial stocks was warranted, with a global outlook. These investors likely purchased those calls expecting to profit from their idea, but maintained a defined risk amount, or one percent of the underlying shares, should their theory prove to be unfounded by the rest of the market.

Those calls traded up to $1.30 on Monday, October 1, more than twice their purchase price. The stock rose 2.8% at the same time, illustrating the kind of leverage that can be achieved with options.

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Long calls lock in the price where a stock can be purchased, gaining with a rally and providing leverage to the underlying shares. The contracts can quickly lose value if the stock stalls or pulls back but also carry less risk than owning the shares themselves.

The Wisdom Tree Japan Hedged Equity Fund was up 1.28% to $58.69 on Monday. The exchange-traded fund tracks large-cap Japanese stocks while adjusting for currency fluctuations.