On Friday, the unusual buying of strong options in Leap Wireless International Inc, a prepaid wireless carrier, before AT&T's buyout bid raised eyebrows. It was speculated that the report reached the traders in advance.

Over the last three months, the average option volume in Leap was 1,320 contracts per day.

However, during Friday's trading session, Leap's option volume climbed to 7,139 contracts. Out of the total, only 350 were reported to be puts. This resulted in a call-to-put ratio of 20 to 1. The information came from San Francisco-based Livevol, an options analytics company.

According to many participants in the session, traders concentrated on Leap calls. The calls were higher the value of the stock.

"Based on the unusually high volume of options traded and the out-of-the-money calls that were purchased on Friday, it appears that prior knowledge of this takeover may have been leaked and traded on," Livevol's managing director, Ophir Gottlieb, said.