It was only 11 months ago, on 25 August 2011, that Berkshire Hathaway Inc., Warren Buffett's investment company, agreed to sink $5 billion into Bank of America Corp, the beleaguered financial giant. The deal helped allay fears that America's biggest bank needs a fresh infusion of capital to withstand mortgage losses and another downturn in the economy. The investment was both fresh capital and a market signal -- a reputation thing, if you will.

Last week, Jamie Dimon, CEO of JP Morgan Chase, pulled a Buffet Lite. Dimon, his wife, and a limited-liability company linked to him bought $17.1 million of the bank’s shares after the stock slid amid trading losses. “I expect this is meant as a sign of his confidence in the bank,” John Coffee, a securities-law professor at Columbia University Law School, said in an e-mail to Bloomberg. Like insurances and other financial guarantees, it may be the best PR money can buy.