Where, after applicable limitations period had run, the debtor sought to add an alternative claim of avoidable setoff to a preference complaint, leave to amend would be granted. Since the alternative claim applied to a transfer that had previously been adequately and timely pled as an preferential transfer, it arose from the same set of operative facts and leave to amend was freely granted. The fact that a completely different legal theory of recovery was added to the lawsuit was "factually correct, but also irrelevant." There is no prohibition on a party adding a new legal theory or an entirely new claim for relief in an amended complaint as long as it arises out of the same transaction or occurrence set forth in the original complaint.

However, the debtor's request to add a claim for recovery under 11 USC 549 related to a previously unpled transfer would be denied. That transfer had not been raised in the complaint before limitations ran.