Cross-selling is a sales technique involving the selling of an additional product or service to an existing customer.
Elements that might influence the definition might include the size of the business, the industry sector it operates within and the financial motivations of those required to define the term.
[1] Unlike the acquiring of new business, cross-selling involves an element of risk that could disrupt the relationship of existing clients.
It is commonly felt that the firm's objectivity, being an auditor, was compromised by selling internal audit services and massive amounts of consulting work to the account.
This kind of cross-selling helped major accounting firms to expand their businesses considerably.
Because of the potential for abuse, this kind of selling by auditors has been greatly curtailed under the Sarbanes-Oxley Act.