Kiwibank has set a margin of 290 basis points over the five-year swap rate for the dividend on its upcoming preference share issue. The actual rate for the first five years will be determined on May 3 and will be the higher of 8.13 per cent, which is based on the swap rate of yesterday, or based on swap rate as of that day.The preference shares are being issued by Kiwi Capital Securities but will be ultimately used to provide tier one capital for Kiwibank.The offer of NZ$150 million worth of shares, including oversubscriptions of NZ$50 million, was oversubscribed in the bookbuild process and largely allocated to various financial intermediaries and institutions.Oversubscriptions of NZ$40 million have been accepted and a pool of NZ$10 million has been established for clients of Kiwibank. There will be no public pool.The offer opens today and is expected to stay open until April 30.