A board showing the Real-U.S. dollar and several foreign currencies exchange rates is pictured in Sao Paulo, September 24, 2015. Brazil's depressed currency rebounded on Thursday after the head of its central bank warned that it is ready to use all instruments in its arsenal to curtail the real's collapse as investors fret over the future of Latin America 's largest economy. The real, which earlier in the session had tumbled to a new all-time low of 4.248 to the U.S. dollar, bounced back to 4.069 after central bank president Alexandre Tombini, in an unscheduled press briefing, did not rule out selling part of the country's $371 billion foreign reserves to calm the exchange rate market. REUTERS/Nacho Doce