By Pete Najarian, co-founder of OptionMonsterNEW YORK -- Upside option activity in Bank of America ( BAC) was on fire again Thursday. The October 15 calls really stood out, with most of the large prints purchased for 50 cents to 65 cents as almost 12,000 contracts changed hands, according to OptionMonster's real-time tracking systems. There was also heavy buying in the Weekly 15 calls that expire next Friday, which saw more than 20,000 contracts go for 4 cents to 14 cents. These calls lock in the price where shares can be purchased no matter how far the stock might rise, potentially profiting from a move higher for much less cost than buying shares outright. The leverage can be extreme if traders time the rally correctly, but the contracts can end up worthless if the shares fail to gain enough by their expiration dates. The bank's stock rose 3.14% to $14.76 Thursday, closing near the peaks of the session. Boosted by a strong earnings report earlier in the week, shares are now back to their highest levels since early 2011. Total option volume in the name reached 885,400 Thursday, four times its daily average, with 711,000 calls vs. 174,000 puts. More than 1 million contracts turned over in the previous session. Najarian owns BAC calls.