Recently, The Motley Fool had five analysts identify Warren Buffett's best investment. I expected that one of the five would identify Buffett's 2011 deal with Bank of America -- a $5 billion infusion when the bank and market needed it. However, because two of my colleagues identified the deal as the best, I decided that I should take a deeper look at the deal that some people may have forgotten about, especially with all the daily noise that surrounds a stock like Bank of America. A quick rundown of the deal In case you are unaware or simply forgot, Buffett, using the bullet-proof balance sheet of Berkshire Hathaway, provided Bank of America with $5 billion in August 2011. Buffett received some special preferred shares, as well as warrants to purchase B of A common shares. These warrants are redeemable at any time until 2021, allowing Berkshire to purchase 700 million shares of Bank of America at around $7.14 a share.