Trade and investment
Trade and investment is sizable between the two countries now. Singapore is Australia's fourth largest two-way trading partner, with total two-way trade valued at A$31 billion in 2008. Australian service exports to Singapore for 2008 totalled A$3.9 billion, with service imports valued at A$4.7billion. Australian investment in Singapore is close to A$22 billion and Singapore’s investment in Australia is A$43 billion.
Singaporean company SingTel is the owner of major Australian telecommunications company Optus. At the time of purchasing Optus in 2001, the deal was the largest ever for a Singaporean company valued at approximately A$8.5 billion.
In July 2009, the peak clean energy industry bodies in Australia and Singapore signed a memorandum of understanding that will enhance commercial ties between the two countries. Australian Trade Minister Simon Crean said "This agreement sets the framework for collaboration in education, networking and information exchange in sustainable and renewable energy, and energy efficiency issues" 
Singapore and Australia have been partners in the Five Power Defence Arrangements since 1971. In August 2008, Australian Prime Minister, Kevin Rudd and Singaporean Prime Minister, Lee Hsien Loong, met in Singapore to sign a memorandum of understanding to strengthen bilateral defence ties. A joint statement by the Prime Ministers said that the pact aims to enhance the defence relationship between the two countries through 'expanding cooperation and sharing resources to develop military expertise'.
Australian Foreign Minister Stephen Smith describes the two countries as having "a strong bilateral defence relationship". Singapore has also provided support to Australian Defence Force operations in Afghanistan.
Ian Patrick Austin. Editor. 2011. Australia-Singapore Relations Successful Bilateral Relations ina Historical and Contemporary Context. Select Publishing. Singapore. Chapter 1 Australia-Singapore Relations - Diplomatic, Strategic, Commercial and Cultural (Ian Austin) Chapter 2 Australia and Singapore: the Development of Political Relations (Stephen Dobbs) Chapter 3 The Singapore-Australia Defence Relationship: Its Origins and Development Chapter 4 Australia-Singapore Commercial Relations (Ian Austin) Chapter 5 Entrepreneurship and the Growth of nations: A Comparative Study of the Small Business Sector in Australia and Singapore. (Calvin Wang) Chapter 6 Australia-Singapore Civila Aviation Relations. (Ian Austin and Yong Han-Cheong) Chapter 7 Food Stories: Culinary Links of an Island State and a Continent. (Cecilia Leong-Salobir) Chapter 8 Singapore and the LASALEE College of Arts: Australian Students Studying Musical Teatre Performance in Singapore. (Aaron Hales) Chapter 9 Creative Human Exchanges and the Singapore-Perth Network. (Terence Lee) Postscript: The Proposed ASX-SGX Merger - An Australian Perspective. (Ian Austin and Simon Minaee)