NEW YORK -- Cowen and Company, an investment banking, brokerage and research firm, has downgraded Visa and MasterCard stocks from out performing other stocks to under performing them.

According to press reports, the firm downgraded the stocks based on what it considered deteriorating fundamentals, essentially making the judgment that the card brands are not immune from the overall economic downturn.

For MasterCard, the firm estimated that strength in the company's non-US purchase volume has been offsetting a material deterioration in US-based purchase volumes and that these weakening trends will make it difficult for the card brand to meet its income targets.

For Visa, the company doubted that consumers' continuing attraction to debit cards would be enough to shield the card brand from loss of income. In the end, the company estimated, declining employment figures cannot help but impact the ability of consumers to spend, including on their debit cards.