Nasdaq OMX Group (NDAQ) was the focus of some heavy put trading on Wednesday, as more than 4,400 contracts changed hands. This volume is nearly three times the equity's average daily trading volume, according to data from WhatsTrading.com. Furthermore, roughly 90% of the volume changed hands at the ask, indicating that these bearish bets were most likely purchased.

In the front three months of options, the most active option was the August 20 put, which added roughly 3,500 new positions. Open interest for this back-month option now stands at 4,239 contracts. At 10:15 a.m. Eastern time, several large blocks totaling 3,168 contracts changed hands at an ask price of $1.20.

This surge in put buying caused the stock's Schaeffer's put/call open interest ratio to jump overnight from 0.68 (in the 18th annual percentile rank) to 0.87 (in the 56th annual percentile rank).

Put trading has also been brisk on the International Securities Exchange (ISE) and the Chicago Board Options Exchange (CBOE). The 10-day ISE/CBOE put/call volume ratio comes in at 1.37, as nearly 1.4 puts have been purchased to open for every one call purchased to open. This ratio is higher than 84% of all those taken during the past 12 months, indicating a growing skepticism among investors.

Technically speaking, the shares of NDAQ are down more than 16% since the start of 2009, underperforming the broad market. The stock is down 0.34% in morning trading as the stock struggles to hold support at its 10-week moving average.