Financial services group Australian Unity has tapped the little-used simple bond market, launching two new series bonds on the Australian Securities Exchange.The health insurer, fund manager, banker and retirement living group is seeking to raise a total of A$250 million, with a minimum issue of $50 million, with the launched of Series C Australian Unity Bonds and Series D Australian Unity Bonds.Part of the proceeds will be used to refinance an earlier issue, Series B Australian Unity Bonds, and for general corporate purposes.The floating rate bonds, which have a face value of $100, are unsecured notes which have been assigned a BBB+ credit rating by Australia Ratings.Series C notes will mature in December 2024 and are expected to pay a margin between 200 and 220 basis points over the 90-day bank bill swap rate.Series D notes will mature in December 2026 and are expected to pay a margin between 215 and 235 bps.Acacia Partners and NAB are the joint arrangers and joint lead managers. ANZ Securities and Evans Dixon Corporate Advisory are joint lead managers.The offer will open on September 17, with ASX trading expected to start on October 18.Simple corporate bonds were introduced in 2013, following law reform that introduced a simplified disclosure regime, changes to directors' civil liability provisions in respect to bonds issued to retail investors, and provision for the bonds to be issued on the ASX.They were introduced as a way of opening up a retail corporate bond market and providing greater liquidity for issuers.The ASX is home to a small number of corporate bond issuers, including real estate developer Peet Ltd, Mercantile Investment Co, US Master Residential Property Fund, Villa World, litigation funder IMF Bentham and business lender Axsesstoday.Australian Unity's latest financial report shows that profit grew 2.8 per cent to $53 million in 2018/19, on revenue of $1.6 billion.Its banking subsidiary, Australian Unity Bank, grew assets 14 per cent to $886 million and increased customer numbers by 1.2 per cent to 24,400. It currently has no secured or unsecured debt that ranks ahead of the bonds.