By Pete Najarian, co-founder of OptionMonsterNEW YORK -- Ford ( F) has been on a stealth run, and on Thursday activity built rapidly in the options. OptionMonster's tracking systems showed steady flow in the May 14 calls, with early buyers paying 9 cents to 12 cents. Volume topped 25,000 barely an hour into the session and ended the day close to 39,873 contracts -- well above the strike's previous open interest and therefore new positioning. Calls lock in the price where shares can be purchased. That can give them leverage to the upside, something that we saw Thursday because the stock inched higher and those calls rose more than 10% to 14 cents. Ford shares gained 1.05% Thursday to close at $13.47. It has not made any explosive moves this year, but quarterly results were strong earlier in the week thanks to a rebound in North American sales. Thursday's option activity was skewed toward the calls by more than 5 to 1, a reflection of the session's bullish bias. Total volume was almost triple the normal amount. Najarian owns F calls.