Federal regulators have begun to look at Warren Buffett's Berkshire Hathaway to see if its failure would be damaging enough to threaten the country's financial stability, according to a report by Bloomberg.
It quotes "two people with knowledge" of the matter as saying the staff of the U.S. Financial Stability Oversight Council, led by Treasury Secretary Jack Lew, wants to determine if Berkshire is so important to the health of the financial system that it needs special supervision by the Federal Reserve.
The Fed could demand stress testing and impose strict capital, leverage and liquidity requirements.
Berkshire runs the world's fourth biggest reinsurance operation.
The Bloomberg report notes that any decision could be months away and the study doesn't necessarily mean the FSOC is leaning toward a "too big to fail" designation.
CNBC's call to Berkshire for comment was not immediately returned.
You can read the complete Bloomberg report here.
—By CNBC's Alex Crippen. Follow him on Twitter: @alexcrippen