Spain saw its cost of borrowing fall further, a day after the European Central Bank unveiled a new bond-buying program that is largely designed to keep a lid on the country's borrowing rates, AP reported. Investors think Spain will make a formal request to tap the new program within weeks, which could ease the pressures in the eurozone's fourth largest economy. Spanish officials have given no guidance on when they could make a formal request for the ECB to buy the nation's bonds. However, expectations it will have had a marked impact on its borrowing rates over the past few weeks. The yield on Spain's ten-year bond fell another 0.21 percentage point Friday to 5.80 percent, the first time it's gone below 6 percent since May. A rate above 7 percent is widely-considered unsustainable in the long-run.