Put options have become a popular choice on Delphi Automotive PLC (NYSE:DLPH - 35.84) in recent sessions, according to data from the major options exchanges. During the past five days, speculators on the International Securities Exchange (ISE) and Chicago Board Options Exchange (CBOE) have bought to open 3,304 puts on DLPH, along with just 13 calls -- netting the stock a five-day put/call volume ratio of 254.15.

In fact, over the past 10 sessions, options traders on the ISE, CBOE, and NASDAQ OMX PHLX (PHLX) have bought to open 27.88 puts for every call on DLPH. This ratio is now hovering near its highest level in six months, pointing to a stronger-than-usual preference for bearish bets over bullish in recent weeks.

It's interesting to note that DLPH has been trekking steadily higher amid this rush of pessimistic speculation, with the stock now sitting on a year-to-date rise of 67.3%. Since August, the equity's uptrend has been highlighted by support at its rising 20-day and 50-day moving averages.

On the news front, DLPH is due to join the S&P 500 Index (SPX) after the market closes today, replacing Titanium Metals (NYSE:TIE) in the venerable index. This could provide a natural buying boost for the stock during the near term as fund managers adjust their portfolios accordingly.