$ALXN call prices soar over the weekend

Option traders racked up huge profits today on bullish positions opened in Alexion Pharmaceuticals(ALXN) only one session earlier.

On Friday morning, Dec. 11, our Unusual Activity scanners found that 3,700 January $130 calls were bought for $1.75 to $3.20 part of a bullish roll above open interest of 2,958 contracts as part of a bullish roll with shares at $120.21.

Those calls have surged to trade to $30.30 today, at least 9 times their purchase prices. The stock rose 33.03% in the same time frame, underscoring how quickly options can far outperform their underlying shares.

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.

ALXN jumped 30.10% to $157.40 today. The pharmaceutical company has entered into an agreement with AstraZeneca (AZN) to be acquired for $175 per share in cash and stock.