Warren Buffett poured $3 billion into Dow Chemical during the financial crisis. Here's the story of how he helped the manufacturing titan – and doubled his money.

• Warren Buffett invested a vital $3 billion in Dow Chemical at the height of the financial crisis.
• In return, Berkshire Hathaway received preferred stock paying a yearly dividend of 8.5%.
• Buffett's company ultimately made an estimated $3 billion profit from stock sales and dividends.

Warren Buffett poured $3 billion into Dow Chemical in the depths of the financial crisis, helping the manufacturer to complete an acquisition at a time when investors, lenders, and companies were taking cover.

Here's the story of one of Buffett's signature deals, which provided much-needed cash to an ailing company – and earned him a healthy return.