by Jason Simpkins
On Wednesday, every former treasury secretary since 1995, plus representatives from the Nixon and Carter administrations, signed off on a letter imploring Great Britain to stay in the EU.
The group included Larry Summers, Robert Rubin, Henry Paulson, and Timothy Geithner, among others.
The letter was published just as President Obama arrived in the UK, where he too argued against a Brexit.
So why all the fuss? What are they all so worried about?