It's been a bumpy ride for MBIA Inc. (NYSE:MBI - 9.93) this year, with shares of the financial-services firm racking up a loss of 13.2% so far in 2012. Rather than a steady downtrend, MBI's path on the charts has been a hectic zigzag, punctuated by several gaps -- both bullish and bearish. Most recently, after spending the month of July stumbling lower, MBI popped higher on Thursday after unveiling its latest quarterly report.

This event -- and the ensuing gap higher -- may have been the catalyst behind a rollout on MBI during the course of Thursday's session. At 2:46 p.m. Eastern, a block of 4,875 August 10 calls traded near the bid price at $0.45, indicating they were sold. Simultaneously, a symmetrical block of 4,875 September 11 calls crossed near the ask price at $0.70, suggesting they were purchased. Open interest at the August 10 call fell overnight by nearly 4,000 contracts, while the September 11 call gained 5,062 contracts.

In other words, this speculator sold to close his August 10 calls, and replaced them by buying to open an equal number of September 11 calls. By rolling his calls up and out to the back-month series, the trader is not only raising his bullish forecast for MBI -- he's also buying more time for that rally to play out.

From a broader perspective, calls have been gaining popularity in recent weeks. MBI has racked up a 10-day call/put volume ratio of 9.42 on the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX). This ratio arrives in the 67th percentile of its annual range, indicating that options players have bought to open calls over puts at an accelerated pace lately. However, with 15.1% of the equity's float sold short, some of those calls may have been purchased by the bears to hedge their shorted shares.