It was a week for tier two and additional tier one capital issuance in the debt capital market last week.IMB Bank started it off with a small tier two capital issue. The bank sold A$30 million of BBB- rated notes. The notes will yield 375 basis points over bank bills and are callable after five years but have a ten-year maturity.  Auswide Bank followed towards the end of the week with a $13 million tier two issue. The BB+ rated notes were priced at 480 bps over bank bills.In New Zealand, Cooperative Bank issued NZ$30 million of BB+ rated tier two capital. The notes will yield six per cent.In the ASX-listed sector, National Australia Bank completed the bookbuild for its Capital Notes 2 issue early. The bookbuild closed at $1.35 billion (launch size was $750 million) and the credit margin was set at the low end of the 495 bps to 510 bps indicative range.NAB also completed the prime RMBS issue via National RMBS 2016-1 Trust, launched the week before. The issue was upsized to $2 billion from $730 million.The issue includes $1.8 billion of A notes, which priced at 127 bps over 30-day bank bills. Pricing on the $120 million of B notes and $40 million of C notes was not disclosed. The weighted average life of the notes was not disclosed.The New Zealand dairy giant, Fonterra Co-operative Group (rated A-), undertook only its third kangaroo issue, selling A$125 million of ten-year bonds. The bonds were priced at a margin of 170 bps over swap.Offshore, Transurban Finance Company (rated BBB) sold CHF200 million of seven-year bonds, priced at a margin 98 bps over mid-swaps in the Euromarket. The pricing, swapped back into Australian dollars, equates to about 234 bps over bank bills. This appears expensive when compared with the 180 bps achieved by Port of Brisbane (rated BBB) for seven year funds in the domestic market. This issue was sold just two weeks earlier.Westpac New Zealand sold €750 million of five-year covered bonds. The EFRNs priced at just 18 bps over mid-swaps.ASB Bank (rated AA-), raised €500 million for four years. The Eurobonds will yield 60 bps over mid-swaps.Lastly, Rio Tinto announced a US$3 billion debt buyback. In the first instance Rio is seeking to buy back all or some of US$1.7 billion of 6.5 per cent notes due in 2018, and US$1.2 billion of 2.25 per cent notes due in 2018. Rio is offering to buy the notes back at a spread of 50 bps over the 31 May 2018 US Treasury bond.Rio will then look to successively buy back other notes issues.