Average yields on a 0.25 percent three-year bond due Jan. 31, 2019 fell to -0.072 percent, compared to 0.137 percent when the paper was last sold in mid-June. The Spanish treasury sold 1.7 billion euros of the bond, with demand exceeding the offer by 1.7 times versus 2.1 times previously.
The auction comes at a time of massive bond buying by the European Central Bank as fights weak growth and inflation across the euro zone.
Despite Britain's vote to leave the European Union, which has heightened expectations of eventual central bank action to propel the bloc's modest recovery, the ECB is widely expected to hold fire on further stimulus measures at a meeting later on Thursday.
The Spanish treasury also sold 907 million euros of a 0.75 percent July 30, 2021 bond, with yields on that five year paper also hitting a record low of 0.227 percent. The bid-to-cover ratio, a measure of demand, was 3.3 times compared to 2.3 times at its previous outing earlier in July.
An Oct. 31 2046 bond with a 2.9 percent coupon sold at an average yield of 2.275 percent, down from 2.722 percent at the last auction in early June. The treasury sold 455 million euros of that paper, and the bid-to-cover ratio was 2.3 times, versus 1.6 times previously.