By Jud Pyle, CFA, chief investment strategist for the Options News NetworkShares of super-regional bank PNC Financial Services ( PNC) are currently down over 15% to $16.80 after falling as low as $16.20. The slide in the stock has spurred some put-buying that suggests that more downside slides, or at least more volatility, will be in the offing for PNC. Looking at the PNC April 10 puts, we see that over 19,000 have traded in the first four hours of trading. The puts are currently trading for around $1.75, with the stock near $16.80. The current open interest in the puts is just 141, according to the Sidewinder report at www.onn.tv.