The shares of Trina Solar Limited (ADR) (NYSE:TSL - 4.67) followed the broader equities market higher yesterday, bouncing back from March 2009 territory. What's more, it looks like some options speculators are expecting the solar stock to extend its rebound over the short term, with front-month calls picking up steam.

By the closing bell, TSL had seen more than 1,800 calls cross the tape -- more than twice its average daily call volume, and close to three times the number of TSL puts exchanged. Most of the action centered on the near-the-money August 5 call, which saw nearly 1,200 contracts traded -- 94% at the ask price, suggesting they were bought. Plus, call open interest at the front-month strike soared overnight, confirming our theory of newly initiated positions.

By purchasing the calls to open, the traders are betting on TSL to surmount the $5 level within the next few weeks. Specifically, the volume-weighted average price of the calls was about $0.08, meaning the buyers need TSL to muscle atop the $5.08 level before the calls will become profitable. In any event, the most the investors can lose is capped at the initial premium paid for the calls.

From a broader sentiment standpoint, yesterday's preference for short-term calls was nothing new for TSL. The stock's Schaeffer's put/call open interest ratio (SOIR) of 0.64 indicates that calls comfortably outnumber puts among options expiring within three months. What's more, this ratio sits just five percentage points from a 52-week nadir, suggesting near-term options players have rarely been more call-biased during the past year.

On the other hand, short interest edged 2.7% higher during the most recent reporting period, and now accounts for nearly one-fifth of TSL's total available float. In fact, it would take about two weeks to repurchase all of these pessimistic positions, at the equity's average daily trading volume. As such, it's possible that some shorts have been hedging their bearish bets with short-term calls.