National Australia Bank will raise up to $500 million by issuing subordinated notes to investors.

The issue of the unsecured, subordinated debt obligations has the ability to raise more or less than $500 million, NAB said on Monday.

“The offer provides investors with the option of a simple, attractive, yield-based subordinated debt investment in a major bank which can diversify an investment portfolio and provide the benefit of a regular, quarterly interest payment,” NAB’s executive director of finance Mark Joiner said in a statement.