The National Treasury Management Agency said it sold €500m of 12-month Treasury bills as planned today.
The bills were sold at a yield of -0.36%, the NTMA said in a statement.
Total bids received amounted to €1.587 billion, which was 3.17 times the amount on offer.
The agency sold the same amount of six-month paper in June at a yield of -0.22%.
Last week, the NTMA sold €1 billion of 10-year debt at a yield of 0.33%.
That was below the 1% it paid at the last regular auction of its 2026 bond in February.
The NTMA has now raised €7 billion out of a guided range of €6 billion to €10 billion of debt for the year.