SO WHY IS SPAIN'S BANKING CRISIS SO WORRISOME TO EVERYONE ELSE?Spain is the fourth-largest economy in the 17-country eurozone, behind Germany, France and Italy. Its economy is nearly five times bigger than Greece's, making its financial and economic problems much more worrisome for leaders in Europe. The rising cost of rescuing failed banks risks bankrupting the Spanish government. And since Spanish banks own huge amounts of their country's debt, any threat to the government's finances could boomerang back to the banks and make them even weaker. A widening recession and financial crisis in one of Europe's largest economies would drag down neighboring countries and hurt companies and investors around the world. An international bailout of Spanish banks could relieve some of the pressure on the Spanish government, and decrease anxieties across Europe and the rest of the world. HOW MUCH WILL IT COST TO BAIL OUT SPAIN'S BANKS? Bankia S.A., the country's most stricken lender, announced last month that it needed â¿¬19 billion ($23.63 billion) in government aid. Spain only has â¿¬5 billion left in a fund that it established in 2009 to help banks. The government has promised to help Bankia but has not mapped out a plan. At least four other Spanish banks also need help. The overall cost of bailing out Spain's troubled banks is somewhere between â¿¬40 billion and â¿¬100 billion. The International Monetary Fund is scheduled to weigh in with an evaluation of Spain's banking industry Monday. And the Spanish government has commissioned independent audits to determine the banks' recapitalization needs. The Spanish government has pushed lenders to strengthen their finances by merging, and has told banks to set aside an additional â¿¬84 billion by the end of 2012 to cover assets that have gone bad, plus those that could turn sour. Spain's two largest banks â¿¿ Banco Santander SA and Banco Bilbao Vizcaya Argentaria SA â¿¿ are expected to meet the stiffer requirements. But investors are fearful that some smaller banks won't be able to.