Fitch Ratings has affirmed the ratings of Macquarie Group Limited and its subsidiaries Macquarie Bank Limited (MBL), Macquarie Financial Holdings Pty Limited and Macquarie International Finance Limited. The agency has provided details behind its assessment of the group's outlook.The ratings agency observed that MBL is the main operating subsidiary of the group and its issuer default rating and senior debt ratings (long term 'A' for both), and viability rating of 'a' reflect a strong risk-management framework, sound liquidity, solid capitalisation and a diverse business mix, both by type of business and geography. "These factors help to offset a level of complexity that results from the diverse business mix, specialised operations outside Australia, a greater risk appetite and earnings volatility relative to Australian retail banks, and a high reliance on wholesale funding," Fitch said.Macquarie Group Ltd is the non-operating holding company of the group. Fitch expects MGL's earnings to remain more volatile than that of Australian retail banks due to the group's greater exposure to investment banking and other market-oriented businesses.Consequently, its IDRs, VRs and senior debt ratings were set one notch down from MBL's ratings "to recognise the regulatory focus on protecting depositors in Australia, limited standalone liquidity (with liquid assets held by the operating subsidiaries), and regulatory restrictions on dividends and liquidity transfers from MBL." "The group's risk-management framework and controls are strong, which is important given a higher risk appetite relative to domestic retail bank peers. New products and businesses are tightly controlled by a centralised risk management group and regular and extensive stress testing is undertaken," the agency noted.Fitch also suggested that MGL "is likely to remain an opportunistic acquirer", although only in areas that build on existing operations, with each transaction specifically funded via new facilities."The group has a strong reliance on wholesale funding but manages risks associated with this well through relatively conservative liquidity management … [such] that it is able to meet all of its obligations over a 12-month period with no access to funding markets, and a modest reduction in the group's core businesses," Fitch reported. In addition, MBL reported that its daily average Basel III liquidity coverage ratio for the final quarter of FY18 was 162 per cent, and its net stable funding ratio was 112 per cent at FYE18.