By December 1930, Irving Trust announced that 80% of the space had been leased in the nearly-completed building. Tenants started moving into 1 Wall Street by mid-March 1931, before its formal opening. Among the tenants were several members of the New York Stock Exchange and Curb Exchange. The Irving Trust Company moved into the building on March 23, 1931. Two hundred guards armed with machine guns moved the bank's $8 billion holdings from its former location at the Woolworth Building. The next day, 1 Wall Street opened to public use, with thousands of visitors. By that time, the building was 90% occupied. Shortly afterward, the Fiduciary Trust Company of New York also moved its banking quarters to the 30th floor, making that space the highest banking quarters in New York City. In a 1938 incident, an electrical transformer on the 21st-story setback blew up; though the windows were shaken, nobody was injured.