The runup this year in Berkshire Hathaway's Class B stock (BRK.B) is a good reminder of the power of an old kind of index arbitrage.
MoreBill Gates, Melinda Gates, and Warren Buffett are asking the nation's billionaires to pledge to give at least half their net worth to charity.
MoreAn anonymous donor bid a record $2.6 million for lunch with the legendary investor.
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