Medical Insurance Australia’s (MIA) A- financial strength rating has been affirmed by Standard & Poor’s (S&P) under its new criteria.

The outlook for the medical indemnity insurer – a subsidiary of Adelaide-based Medical Insurance Group Australia (MIGA) – is stable.

“The ratings largely reflect our view of the company’s satisfactory business risk profile and strong financial risk profile,” S&P Director Financial Services Michael Vine said.

The firm’s acquisition of Invivo in April has enhanced its market position, S&P says, although it remains behind the market leader, which has more than double its forecast premiums and members.

“The stable outlook for MIA reflects our view that the insurer will at least maintain its adequate competitive position in the Australian medical indemnity market,” Mr Vine said.

“We expect MIA to continue to conservatively manage its capital, reinsurance arrangements and reserving practices, while taking a measured approach to growth and new products.

“Government support schemes provide additional stability to the industry, which we expect to continue over the medium term.”

MIA is rated neutral for geographic diversity because, despite “improving diversification” in Australia, it operates in one country only.

S&P’s revised criteria for insurance companies took effect on May 7. They aim to provide more consistent and transparent ratings.