While Cubist Pharmaceuticals Inc.'s $1.6 billion double acquisition of Optimer Pharmaceuticals Inc. and Trius Therapeutics Inc. has gone down on the books as one of the biggest biotech events of the year, some analysts are crying foul at Optimer's surprisingly low selling price of $10.75 per share, or 20 percent below the stock's closing price of $13.29 on July 30, but it is barely more than 50 percent of the $20 per share offer Cubist made earlier this year.