Reuters:The Blackstone Group has announced plans to buy Dallas-based Alliance Data Systems Corp., a business-services company that provides transaction, credit and marketing services, for $6.76 billion. The purchase plan follows the $683 million TransFirst buyout announced earlier this week. But according to a May 18 Associated Press update, one industry analyst suspects a rival bidder could pull the deal out from under Blackstone's feet, saying that ADS is worth more than what Blackstone is offering.