Transurban did become the first true corporate to issue in the domestic corporate bond market in 2010 but another issuer pipped Mirvac to the post for second. SPI Australia Electricity & Gas Holdings Pty emerged as the second vendor of corporate bonds for 2010 and sparked some discussion on credit spread levels.On Monday, Transurban Finance (rated A-) upsized and priced its four-year bond issue launched last Thursday. Transurban raised a total of $250 million, at the indicated margin of 180 basis points over swap.  On Wednesday, SPI Australia Electricity & Gas Holdings, (also rated A-) launched a A$200 million to $300 million, 7.5-year bond issue with an indicative credit spread of 165 bps over swap. The issue was capped at $300 million on Thursday, and priced five bps tighter. The pricing of the transaction appears tight against the Transurban bonds and very tight against the only other recent 'A-' rated benchmark, which is Stockland's $300 million, five-year bond issue in December. These bonds were priced at 270 bps over swap.This may suggest that credit spreads have tightened considerably in recent months for bond issues, which provide investors with diversification from financial institutions. But the credit spread is said to be consistent with that being seen on utility issues offshore and with what the company achieved with its own recent offshore issuance. Investors acknowledged this. SPI Australia Electricity & Gas Holdings Pty has been particularly active this year, raising 475 million Swiss francs in February and HK$400 million, just the week before last. In an announcement to the ASX, the company said the issue completes its funding requirement for fiscal 2011. Mirvac (rated BBB) was third to the market, raising $150 million for five years priced at 265 bps over swap.  No doubt Mirvac wishes it was a utility rather than a property developer. As a further test of the market's appetite for corporate risk, Adelaide Airport (BBB) is seeking to buy back A$240 million of bonds maturing in December 2010 and to sell new bonds with a 5.5 year term to maturity. The old bonds were credit wrapped while the new bonds will reflect solely the credit risk of Adelaide Airport: a credit spread of 250 bps to 270 bps over swap/bank bills is being offered.Adelaide Airport also has $265 million of September 2016 credit wrapped bonds outstanding.