Turkey’s credit ranking was lifted two levels to BB+, due to the resilience of the countries economy during the global financial crisis. The highest speculative-grade status, by Fitch Ratings. Bonds surged the most in two weeks.

Bonds rallied, lowering the average yield on government debt by 12 basis points to 8.84 percent, according to an index of securities tracked by ABN Amro. The lira and shares extended their steepest three-day rally in four months, with the currency strengthening 1.1 percent and the benchmark ISE National 100 index climbing 2.5 percent.

“The rating increase will likely trigger further inflows of portfolio investments into Turkish assets,” said Mehmet Ilgen, a trader at Ata Invest in Istanbul. “It will open the way for investment-grade ratings for Turkish corporates, which will decrease external financing cost for companies.”

Turkish banks endured the global economic crisis without financial aid from the government, unlike the country’s recession in 2001 which prompted a bailout of lenders and tougher industry controls. Slowing inflation enabled the central bank to lower the benchmark borrowing rate by 10.25 percentage points, the biggest reduction among the Group of 20 largest economies, helping to ease the downturn.

“The upgrade reflects Turkey’s relative resilience to the severe stress test of the global financial crisis,” Edward Parker, head of emerging Europe sovereigns at Fitch in London, said in a statement today. “Credit fundamentals and debt tolerance are stronger than previously thought.”

Moody’s Investors Service rates Turkey’s debt at Ba3, three steps below investment grade and Standard & Poor’s applies an equivalent BB-.