The Australian Office of Financial Management sold $600 million of February 2017 Commonwealth government bonds at an average yield of 4.29 per cent with the issue 3.7 times oversubscribed on Wednesday. On Friday, it sold $599 million of May 2013 bonds at an average yield of 3.84 per cent with the issue 3.4 times oversubscribed.The Australian branch of Rabobank added another $50 million to its February 2012 Euro medium term note program to take outstandings to $325 million.An announcement by S&P on Friday alerted the market to a US private placement being undertaken by Caltex Australia Ltd. Caltex is looking to issue US$150 million of bonds with maturities ranging from 2014 to 2016. Pricing of the BBB+ rated bonds is expected on Thursday. Broadcast Australia Pty Ltd has launched a buyback of its Ambac wrapped July 2009 bonds. There is $250 million of bonds outstanding and Broadcast Australia is hoping to buy back at least $100 million of the bonds at a clean price of 99.750.It is not clear why Broadcast Australia is seeking to do this, although it is subject to an agreed takeover bid from the Canada Pension Plan Investment Board. There is a further $250 million of bonds outstanding and due to mature in July 2012. Perhaps these too will become the subject of a buyback.The bonds were rated triple A when originally issued with the Ambac credit wrap but Ambac's credit ratings have since fallen to 'A' from S&P and 'Baa1' from Moody's. Broadcast Australia is rated 'BBB' by S&P and 'Baa2' by Moody's, in its own right. Moody's has indicated that it expects to affirm its rating with a stable outlook should the offer from CPPIB become unconditional.