In a note, published Tuesday, Old Mutual stated that it believes “that this action is without merit and we will resist accordingly”.
There are no details at present about the specific nature of the claim.
Old Mutual advised that it will update the market in due course and reiterated that the managed separation, which will see the insurer split into four businesses, “remains on track for material completion by the end of 2018”.
The claim, lodged in New York, is from US insurance firm The Travelers Companies and St. Paul Fire and Marine Insurance Company.
Founded in 1853 and 1565, respectively, St. Paul Fire and The Travelers Companies merged in 2004, and rebranded as The Travelers Companies four years later.
It provides property casualty insurance for auto, home and business.
According to its website, Travelers insured the moon landing in 1969 and a Harley Davidson belonging to Elvis.
The company also paid out $1.1m to beneficiaries of some of those who drowned after the sinking of the Titanic in 1912. Adjusted for inflation, this would equate to around $27.5m (£19.8m, €22.3m) in current money.