Warren Buffett's Berkshire Hathaway has converted much of its debt in building products company USG into more than $600 million of common stock in a successful investment made in the wake of the financial crisis.
US Gypsum (USG) dry wall board plant at Plaster City, near El Centro, Calif.Getty Images
According to regulatory filings on Tuesday and Thursday, Berkshire acquired 21.39 million USG shares last month by exchanging $243.8 million of convertible notes it held in the Chicago-based company.
That boosted its USG stake to 38.46 million shares, or more than 27 percent, worth $1.09 billion as of Tuesday's close.
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The stake makes Berkshire the largest shareholder of USG. It could rise above 30 percent if Berkshire were to swap its remaining $56.2 million of USG notes, a filing shows.
A USG spokesman declined to comment on Berkshire's stake. He said USG has roughly 139 million shares outstanding on a fully diluted basis following last month's redemption.