MADRID, Sept 6 (Reuters) - Spain's debt costs at auction dropped sharply on Thursday from previous outings, aided by hopes the European Central Bank will unveil a significant bond-buying plan later in the day.
The Treasury sold 3.5 billion euros ($4.4 billion) in three bonds. It had hoped to raise between 2.5 billion and 3.5 billion euros through the sale of the bonds due 2014, 2015 and 2016.
Spain sold 682 million euros of the bond maturing April 30, 2014, at an average yield of 2.798 percent, compared to a yield of 4.706 percent when it was last sold at auction in June. The bond was 2 times subscribed after being 4 times subscribed previously.
The bond maturing July 30, 2015, sold at an average yield of 3.676 percent, down from 5.086 percent at its last outing in July. The Treasury sold 1.4 billion euros of the paper while bids were 1.8 times more than that compared to 2.3 times at the last auction.
The longer-dated bond sold at an average yield of 4.603 percent compared to 5.971 percent last month. Traders bought 1.4 billion euros of the bond, which is due Oct. 31, 2016, at a bid-to-cover ratio of 1.9 after 2.7 previously.
The euro zone's fourth largest economy is on the front line of the euro zone debt crisis on concerns it cannot finance itself at current levels and will be forced to apply for a sovereign bailout which would stretch existing European funds to breaking point.