An abrupt jump in corporate financing exposure could hurt the capitalization of the two biggest Korean securities firms, S&P Global Ratings said in a Thursday release.

Mirae Asset Securities (KRX:006800) and Korea Investment & Securities recently received a green light to market the newly introduced investment management account (IMA) products, subjecting them to risky corporate financing or "venturous financing," S&P said.

Credit analyst Sunghyun Park said the securities firms have enough buffers against a moderate rise in risky equities or funds, but an aggressive increase could pressure their ratings.

Risk-adjusted capital ratios that are persistently under 7% could prompt the rating agency to lower the ratings, credit analyst Daehyun Kim said.

A 40% investment of IMA-raised funds into equities or funds could reduce the RAC ratios to about 7.4% for Mirae and 7.1% for Korea Investment & Securities from 9.1% and 9.3% at end-2024, S&P said.