The larger NRSROs have also been criticized for their reliance on an "issuer-pays" business model, whereby the bulk of their revenue comes from the issuers of the bonds being rated, so that the company receiving the credit rating pays the CRA directly. While this is recognized by regulators as a potential conflict of interest (since the bond issuer paying for the rating has an incentive to seek out the CRA most likely to give it a high rating, possibly creating a "race-to-the-bottom" in terms of rating quality), the larger NRSROs claim that the issuer-pays model is the only feasible model for them, because, in an age of email and faxes, the ratings of the larger CRAs are so widely and so quickly shared that a subscription-based model would not be profitable. Conversely, the predominance of the issuer-pays model has led to concerns that a CRA will be tempted to artificially inflate its rating to retain a valued customer.