BlackRock funds have incurred losses of about $17bn due to their holdings in Russian companies, with the world's largest money manager having to write down assets in a market that has become uninvestable following the invasion of Ukraine.

The New York-headquartered asset manager held more than $18.2bn in Russian assets at the end of January, but that value has fallen to around $1bn at the end of February. The change in value is a result of BlackRock marking down holdings, rather than any sale of assets.