Calls were in focus on Under Armour Inc (NYSE:UA - 47.02) on Tuesday, as option players placed bets on a strong earnings showing by the athletic apparel maker. Almost three-quarters of the roughly 5,400 calls that traded on the day crossed at UA's February 50 call, the majority of which went off at the ask price. Implied volatility jumped 3.5 percentage points at this strike, and open interest added 2,912 positions overnight, indicating buy-to-open activity.

By purchasing these out-of-the-money calls to open for a volume-weighted average price (VWAP) of $0.77, traders need UA to muscle above $50.77 (strike price plus the VWAP) by the close on Friday, Feb. 15, at which point these options expire. This breakeven mark represents an 8% premium to current levels.

Data from the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX) reveals Tuesday's bullish disposition is just more of the same for option traders. The stock's 10-day call/put volume ratio of 1.54 ranks higher than 65% of other such readings taken in the past year, suggesting a healthier-than-usual appetite for calls over puts in recent weeks.

This rush toward calls is a bit puzzling given UA's recent showing on the charts. Despite being up around 24% year-over-year, the stock has shed roughly 23% of its value since hitting a record peak of $60.96 in mid-September. Additionally, the equity has not finished north of the round-number $50 mark on a daily closing basis since Dec. 12.

UA is slated to take its turn in the earnings confessional ahead of the bell on Thursday, Jan. 31. The company has bested analysts' bottom-line projections in each of the last four quarters, and yesterday's call buyers could be hoping the trend continues. Wall Street is calling for a profit of 46 cents per share in UA's fourth quarter.

Should the stock fail to break through the $50.77 level by February expiration, though, the most traders have risked is the initial premium paid.