Standard & Poor’s Ratings Services has affirmed the AAA rating it has assigned to Northwestern Mutual Life Insurance Company.

Northwestern Mutual, Milwaukee, has reported that money market funds at its Russell Investments subsidiary have about $764 million in direct credit exposure to the turmoil at Lehman Brothers Holdings Inc., New York.

“Net losses and any recovery are uncertain at this time,” according to S&P, New York.

Despite the Lehman-related losses, “Northwestern maintains capital that comfortably meets Standard & Poor’s requirements for [an] AAA rating, and we consider it one of the most well capitalized companies in the life insurance industry,” S&P says. “We believe Northwestern has the capacity to fulfill its obligations under the support agreements and maintain the current ratings.”