By David Russell, reporter at OptionMonsterNEW YORK -- BMC Software ( BMC) has rallied despite weak results, and buyers returned to the name last week. OptionMonster's tracking programs detected the purchase of 10,000 January 45 calls for $2.25 and the sale of an equal number of January 50 calls for 60 cents on Friday. Volume was more than triple open interest at both strikes, indicating that this is a new position. Owning calls gives the right to buy a stock at a certain level, while selling them obligates a sale if the shares reach the strike price. In the case of Friday's trade, known as a bullish vertical spread, the calls have locked in the right to buy BMC for $45 if it closes at or above that level in mid-January. If it goes above $50, the trader must exit for that price. The net effect is that the trader spent $1.65 and will collect $5 if BMC is at or above $50 at expiration -- about 15% over Friday's closing price. However, this call spread will more than triple in value from that move, which illustrates the kind of leverage that can be achieved with options. BMC slipped 0.12% to $43.34 on Friday. The bullish option trade was especially interesting given the weakness in other enterprise-software companies recently. BMC's last earnings report in July was bad as well, yet the stock quickly rebounded. Its next set of numbers will probably be released later this month based on last year's calendar. Overall option volume in the company, the subject of sporadic takeover speculation, was 19 times greater than average. Calls outnumbered puts by 40 to 1. Russell has no positions in BMC.