By David Russell, reporter at OptionMonsterNEW YORK -- The bulls hit a home run in ValueClick ( VCLK) Monday, using option leverage to amplify a rally in the share price. The stock started the day quietly, opening higher by less than 1% before the buyers showed up. Early prints in the April 29 calls showed blocks pricing for $1, while the April 30s went for 80 cents. Volume was especially noteworthy at the higher strike, where more than 3,400 contracts traded against previous open interest of just 596. The shares were up more than 6% when the calls hit and continued to work their way higher, at one point showing a gain of almost 12%. But that move was nothing compared with the options because both call contracts more than doubled in value as the stock advanced. The 29s fetched as much as $2.15, while the 30s shot up to $1.65, according to OptionMonster's tracking systems. Because they cheaply fix an entry level on a stock, calls can generate significant leverage if investors correctly anticipate fluctuations in the share price. They can also lose most or all of their value if the move doesn't occur. ValueClick's shares closed Monday's session at $30.12, a gain of 8.54%. The main catalyst driving the rally was an upgrade from Jefferies, which also raised its price target on the Internet-advertising company to $35 from $23. Total option volume was 14 times greater than average, with calls accounting for more than 90% of the volume. Russell has no positions in VCLK.