WHARF (Holdings) yesterday moved to defend itself against Standard & Poor's (S & P's) decision to make a minor revision to the company's rating outlook. Wharf said its debt-equity and debt-asset ratios were 'by any prudent standards' very low, and had remained so after the recent disposal of the company's interest in Marco Polo Developments. It said that the main impact of S & P's change in outlook was simply that the rating agency 'will closely watch our financial ratios to ensure they do not go beyond our A rating requirements due to our new business diversification'. The company said S & P's formula for calculating net interest cover did not totally reflect reality because of the nature of some of the company's business. The examples it mentioned were that the formula tended to penalise new businesses, especially during their development stage, thus ignoring the credit value of major developments under way and income from company associates - such as Modern Terminals. The company's investment in China had been 'carefully controlled', the Wharf said.