"We've been working on it for five years, " said Janos Kovacs, chief executive at the puzzle-master's Rubik Studio design firm.

WSJ: One Rubik's Cube, Many Knockoffs, Quintillions of Possibilities

Directors should also put in more time: five or six days a year is not enough to master a labyrinthine balance-sheet.

ECONOMIST: How banks can improve their approach to risk management

After finishing the last claim, Kenneth Feinberg, the special master appointed by John Ashcroft, the attorney-general, to run the fund, took a five-day, transcontinental rail trip, his first break since the fund began.

ECONOMIST: A hard task is over: hard questions remain