Wall Street is trying to cope with the considerable ambiguity that officials see in emerging rules on conflicts of interest in securitization and a potentially troublesome federal program that changes how issuers arrange credit ratings for their deals. The conflict-of-interest rule was included in the Dodd-Frank Act as an attempt to prevent participants in the securitization process from structuring deals that allow them to profit at the expense of investors. “When this rule first came out, it was not bad; you could probably live with this in most cases,” said Kenneth Morrison, a...