Warren Buffett's Berkshire Hathaway is showing some confidence in Detroit's attempted comeback as it puts more of its money behind General Motors.
In an SEC filing Friday afternoon, Berkshire said it held 40 million GM shares as of the end of the third quarter on Sept. 30.
That's an increase of 21 percent from the almost 33 million shares it owned three months earlier on June 30.
The additional shares are worth more than $223 million at GM's current price. The full stake is valued at almost $1.3 billion.
Buffett has been a vocal booster of Detroit, visiting several times to promote the "huge potential" he sees in the city.
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In September, he told the Detroit Homecoming conference that "we would buy a company in Detroit today, and we would be happy to have the headquarters here."
Recently, Buffett bought a new Cadillac after meeting with GM CEO Mary Barra. He was "enormously impressed" with her.