Jack Lew was the senior budget adviser to President Barack Obama and President Bill Clinton. He was Obama's chief of staff. Now he is the US treasury secretary. But despite a stellar career, his most remarked-upon trait was his unusual signature, a series of eight connected loops that looked more like an absent-minded doodle than a signature that should grace US banknotes. This week that all changed. The Treasury unveiled Lew's "official" signature, which will be on the US$5 bill this autumn and other currency as it is issued over the years. Lew had promised Obama that he would sign his name more legibly as a condition of his nomination. "Jack assures me that he is going to work to make at least one letter legible in order not to debase our currency should he be confirmed as secretary of the Treasury," Obama joked in January when announcing Lew's nomination. At least one letter, and perhaps two, is legible in the new signature, although one might be hard-pressed to name three. To his credit, the new signature does have three separately identifiable features: a first name, a middle initial - J for Joseph - and a last name. Lew is not the first treasury secretary to change his signature upon appointment. His predecessor, Timothy Geithner, changed his signature, too. Now that he has selected a signature, the Bureau of Engraving and Printing staff will produce new plates for US$5 bills. The new bills will be printed by the bureau, then stored in the vaults of the Federal Reserve, which will decide when to circulate them.