By David Russell, reporter at OptionMonsterNEW YORK -- Homebuilders have been bulletproof recently, and Wednesday the bulls moved into Toll Brothers ( TOL). OptionMonster's tracking systems detected heavy buying in the May 25 calls, which initially priced for $1.40. They later fetched as much as $2.15 as the stock pushed higher throughout the session. Long calls lock in the price investors must pay to buy the stock. That gives them considerable leverage relative to the underlying share price. For example, Toll swung less than 7% in the course of Wednesday's session, but those options appreciated by more than 50%. The stock has remained strong all year and barely flinched as European worries caused the S&P 500 to swoon in recent sessions. Most companies in the industry and related businesses, including home-improvement retailers and suppliers of building materials, have also outperformed. Toll shares closed at $26.96, up 3.37% on the day. At one point in the session the stock touched its highest price since September 2008. Overall option volume was five times greater than average Wednesday, with calls outnumbering puts by more than 10 to 1. Russell has no positions in TOL.