"With Tesco, we definitely made a mistake. I made a mistake on that one more than anybody else made a mistake ... That was a huge mistake by me," the billionaire told "Squawk Box" on Thursday.
The U.K. supermarket retailer has seen its shares fall more than 48 percent year to date. Buffett's investment firm Berkshire Hathaway is now nursing losses of more than $700 million. According to Berkshire's annual letter to shareholders, Buffett has 301,046,076 Tesco shares.