LONDON (MarketWatch) -- Spain's borrowing costs reportedly dropped to an all-time low at an auction of three-year government bonds on Thursday, adding to signs that the euro zone's fourth-largest economy is recovering. The Spanish Treasury sold 2.66 billion euros ($3.62 billion) of a 2017 bond at an average yield of 1.595%, the lowest level since Bloomberg started compiling data in 2004, the news outlet said. The Spanish government also sold €1.81 billion in 2026 bonds and €1.44 billion in 2028 bonds, for a total of €5.91 billion. The targeted range was €4.5 billion to €5.5 billion. In the secondary market, the yield on 10-year government paper es:10yr_esp fell 1 basis point to 3.75%, according to electronic trading platform Tradeweb.