US an­titrust reg­u­la­tors are ques­tion­ing No­vo Nordisk's of­fer to buy the obe­si­ty com­pa­ny Met­sera, say­ing that the struc­ture of the deal — which in­cludes a large up­front cash pay­ment to share­hold­ers of the small­er com­pa­ny — may vi­o­late pro­ce­dur­al as­pects of the law...