Economics Report.A "rollercoaster ride"is one descriptionfor these days of scary upsand downs in financial markets.If you want to usea more technical term,the markets are showing volatility.Thursday was another exampleof a day of strong gainson the New York Stock Exchangeafter a day of heavy losses.Major measures of United Statesmarkets have closedwith their biggest one-day lossessince the financial crisisof two thousand eight.Asia and Europe have also had sharp declines.Volatile markets can react suddenlyin wild and unpredictable ways.Usually some kind of shock,or more than one, is involved.For example, last Friday,one of the three majorcredit rating agenciesdowngraded long-termUnited States government debt.Standard & Poor's lowered its opinionof Treasury securities one stepfrom the highest rating,triple-A, to AA-plus.But shocks like a hopeful jobs reportor good earnings resultscan stop a fall and send prices higher.The United States held S&P'stop rating for seventy yearsand never had a downgrade.But many investors were expectingthat to happen even afterthe budget deal in Washington.Congress last week agreedto increase the government'sborrowing limit in returnfor steps to cut spendingand reduce the deficit.S&P says it thinks America's debtwill only increase in the future.President Obama disagreed.BARACK OBAMA: "It does mean we don't have a problem.The fact is,we didn't need a rating agencyto tell us that we need a balanced,long-term approach to deficit reduction.That was true last week,that was true last year,that was true the day I took office."He said this week that marketsstill consider United States credit"as among the world's safest."Still, there are growing worriesof another recession -- a double dip.On Tuesday, policy makersat the central bank said economic growthso far this year has been"considerably slower"than they had expected.The Federal Reserve saidit would likely keepshort-term interest rates near zerofor at least two more years.Borrowing costs for the United Statesremain very low.But debt worries in two of Europe'sbiggest economies have increased costsfor their governments in recent weeks.On Monday the European Central Bankbegan buying debt securitiesfrom Spain and Italy.These efforts have helped push downinterest rates for those countries.Nick Parsons, an economistwith the National Australia Bank, saysthe bank made the right move.NICK PARSONS: "It has been an absolutelycritical decision."But he also thinks the bankwill have to buy more.And Europe must still dealwith the rescues of Greece,Ireland and Portugal.And that's the VOA Special EnglishEconomics Report.