Weil, 54, was arrested at a luxury hotel in Bologna on October 18 after checking in using his own name, which is on an international fugitive list.
Weil has been wanted by US authorities since being indicted in 2008 for allegedly helping clients avoid taxes as the chief executive and chairman of the global wealth management service at UBS. According to The Wall Street Journal, 85 percent of UBS's American clients hid their identities and bank accounts from the US Internal Revenue Service while the service was under Weil's supervision from 2002 to 2007.
The United States issued an international arrest warrant for Weil, a Swiss national, in January 2009 after the banker failed to appear at a federal court.
The banker has repeatedly denied any wrongdoing. "Mr. Weil agreed to extradition to the U.S. because he has always been prepared to confront these charges," Weil's lawyer said. "We expect him to be fully vindicated when we have the opportunity to present our case to a fair and impartial jury."
According to Reuters, the US has not issued a formal extradition request to Italian authorities, but authorities believe that such a request will occur soon. Prior to his arrest Weil had been living in Switzerland which does not extradite nationals in instances of tax evasion.
Weil's indictment was part of a larger effort to crack down on lenient Swiss banks, described by Reuters as "a landmark in efforts by U.S. authorities."
In 2009 UBS admitted to helping American clients evade taxes and paid US$780 million in fines.