By David Russell, reporter at OptionMonsterNEW YORK -- The bulls are onboard with Overseas Shipholding ( OSG). More than 6,200 options traded in the oil-tanker company Monday, compared with a daily average of about 3,300. Most of the activity focused on the April 11 calls, which traders bought for 40 cents to 50 cents, according to OptionMonster's real-time tracking systems. Almost 3,800 traded against open interest of 2,027 contracts at the strike. These calls lock in the value investors must pay to get long the stock. Because they cost much less than the shares themselves, they can appreciate on a percentage basis much more than the stock if it moves in the right direction. But they will also expire worthless if that doesn't happen. The stock rose 6.11% to $9.03 Monday. It has lost more than two-thirds of its value in the last year and is attempting to rebound from an all-time low established earlier this month. That selloff has left it with a hefty short interest, some 39% of the float. The shares also trade for less than 0.2 time book value. Both of those considerations could help drive it higher. Overall calls in the name outnumbered puts by more than 5 to 1, a reflection of the session's bullish sentiment. Russell has no positions in OSG.