Five days after French authorities foiled a terror plot targeting Bank of America’s Paris headquarters, the threat environment facing U.S. financial institutions in the French capital appears to be worsening. New reporting from Le Parisien says Goldman Sachs’ Paris headquarters was placed under police surveillance on Wednesday night following threats allegedly linked to Iranian terror networks.  Le Parisien outlines the rationale behind the heightened security posture: It’s 1:30 a.m. when the phone rings, shattering the night’s calm. A security guard on duty at the American bank receives a call from his head of security, based in London. According to our information, she informs him that she has received an email from the American authorities, advising him to “extend his vigilance” at the bank. The reason? “An Iranian group is threatening to attack the buildings with explosive devices,” explains a source close to the matter. By Thursday morning, however, the Paris prosecutor’s office said that “no suspicious elements were found at the scene” following surveillance operations in and around Goldman’s building at 85 Avenue Marceau in …