Berkshire Hathaway, the investment vehicle controlled by billionaire Warren Buffet, has purchased 57.6 million shares of UK retailer Tesco Plc, according to a report from Bloomberg news service.

The report cited a filing with the National Association of Insurance Commissioners.

Berkshire Hathaway has recently filed a Form 13F – a filing in which institutional investors that hold more than £100 million worth of stock in public companies are required to disclose their holding at the end of each quarter – but did not disclose any holdings in Tesco. Filers can ask to keep some holding confidential, said the report.