Standard & Poor's Ratings Services on Tuesday downgraded its long-term corporate credit rating of Sony Corp. by one notch to BBB from BBB-plus, citing a slow recovery in the company's mainline consumer electronics business.

The U.S. rating agency said the outlook is "negative" and could lower the rating further if Sony fails to show solid signs of recovery within the next 12 months.

S&P said the downgrading reflects its view that the pace of recovery in the earnings of Sony's electronics business will remain slow for the rest of the business year ending next March, and a strong recovery is unlikely until at least next business year.