Spain on Thursday sold 3.99 billion euros ($US5.16 billion) of bonds at auction.
Investors expect Madrid will eventually request a bailout and this helped push its borrowing costs down for two out of the three bonds sold.
The BBC reports the yield on the two-year bond fell to 3.282% from 5.204% at the last auction in July, and the yield on the five-year bond fell to 4.766% from 6.459%.
But the three-year bond yield edged higher, to 3.956% from 3.845% in July.
