It is not a simple yes/no response from the regulators. First, they will request additional information. That will take some time to prepare. Then they would of

It is not a simple yes/no response from the regulators. First, they will request additional information. That will take some time to prepare. Then they would offer some changes to the proposal. I.e. we cannot approve this deal until some additional requirements are met. Then parties involved evaluate these requirements and counter. At some point business will decide that there are too many constraints and abandon the deal.