Option players have been feverishly accumulating puts on Citigroup Inc. (NYSE:C - 37.73) in recent months, per data at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX). In fact, the stock's 50-day put/call volume ratio of 0.73 ranks in the 93rd percentile of its annual range, implying puts have been bought to open over calls at a near annual-high clip over the past 10 weeks.

This trend was evident throughout the course of yesterday's session, where roughly 50,000 puts changed hands, versus around 43,000 calls. One speculator paid particular attention to the January 2013 series of options, and purchased a block of 15,750 36-strike puts for the ask price of $1.79 per contract. Open interest at this strike surged by more than 15,500 contracts overnight, making it safe to assume new positions were initiated. By buying these puts to open, the trader will profit with each step south of $34.21 (the strike minus the premium paid) C takes through Jan. 18.

On a technical basis, C has had a pretty good run in 2012, with the shares adding nearly 44% on a year-to-date basis. Additionally, during the past 60 trading sessions, the stock has outperformed the broader S&P 500 Index (SPX) by almost 28 percentage points. Helping support this strong price action has been C's 20-day moving average, which has provided a solid foothold for the stock since early August.

Taking C's technical backdrop into account, it may be this uptick in put activity simply represents shareholders protecting their paper profits against a potential pullback. As it turns out, the stock toppled its upper Bollinger Band near the end of October, suggesting C had entered overbought territory. The stock has since consolidated around the aforementioned 20-day moving average.

However, since shareholders are shareholders above all else, they shouldn't be disappointed that C is up 1.1% in today's session to hover near $37.73.