ANZ provided a reminder of the tightening spreads on wholesale bank debt overnight, with the sale of €1 billion in seven-year covered bonds at a spread of 17 basis points over mid-swaps.The bank had pitched the deal at a spread of 20 bps over swaps and received more than €1.5 billion in orders.Westpac sold the first euro benchmark of the year three weeks ago, a €1 billion seven-year bond now trading at 16 to 17 bps over swap, according to the Covered Bond Report.The RBA recently noted that more than three-quarters of recent bond issuance by Australian banks was in unsecured form, with the major banks appearing to be spreading out their covered bond issues in a desire to keep some issuance capacity in reserve in case conditions in capital markets deteriorate again.As of March the banks had issued between 20 per cent to 40 per cent of their regulatory capacity for covered bonds.