Certain key aspects of the deal, particularly a tracking stock, may not qualify for the sort of tax treatment the companies consider essential for the transaction, the report said. “This is a valid worry, but not a deal breaker,” FBR Capital Markets analyst Daniel Ives said. Dell struck a deal to buy EMC in October, setting a record in the technology industry, as it tries to transform itself into a giant in the fast-growing market for managing and storing corporate data.