Why Shares of Citigroup Are Rising Today

Shares of Citigroup (NYSE: C) traded more than 6% higher today as of 10:46 a.m. ET after Warren Buffett and his company Berkshire Hathaway disclosed that they have taken a stake in the struggling bank. Berkshire's first-quarter 13F filing, which shows what stocks the conglomerate bought and sold in the first three months of the year, revealed that Buffett had purchased roughly 55.2 million shares of Citigroup for a total value of nearly $2.95 billion. The purchase equates to roughly 2.5% of Citigroup's outstanding shares.