By Jon "DRJ" Najarian, co-founder of OptionMonster. When there is a takeover at a significant premium, we examine if there was the possibility of someone being tipped off ahead of the event. Sure enough, when Merck ( MRK) bid at a 34% premium for rival Schering-Plough ( SGP), our examination of the data suggests a high degree of likelihood that someone did indeed place what I will generously describe as "nicely timed" trades. In the past 30 days, the average turnover of SGP calls, which give the owner the right to buy shares, was 7,200 contracts a day. Thus, one metric for this news leaking would be to look for days that had larger turnover than that level. We show two such sessions in the final five days leading up to yesterday's announced takeover offer. One was on Tuesday, March 3, when OptionMonster's proprietary tracking systems show that 14,200 calls changed hands -- nearly double normal activity in SGP. The next, and even more telling, action took place last Friday, March 6, when more than 46,000 calls traded. At nearly six times the norm and just a single trading session ahead of the estimated $41 billion bid by Merck, we suspect that so-called informed orderflow indicates something leaked. I leave it to the regulators to decide if that was the case. The heaviest bets were placed at the March 17.50 and April 17.50 call strikes. Those trades paid off like a long-shot bet to win the Super Bowl, as the March 17.50 calls closed Friday at $1.15 but hit $3.70 yesterday morning, a 221% return on investment in just one day.