The 12-country Trans-Pacific Partnership ( TPP), signed on Thursday (Feb 4) in New Zealand, aims to eliminate trade barriers such as tariffs in a bloc that accounts for 40 per cent of the global economy.
Here are some key questions and points:
1. The founding members of the Pacific Rim group are Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, the United States and Vietnam.
2. The far-reaching deal is designed to boost their wealth by doing away with barriers to the free flows of goods, services and investment capital.
Because of its massive scope, members hope it will serve as a blueprint for future global rules for trade and doing business, ensuring a level playing field for all firms, protecting labour rights and keeping free Internet access.
3. The TPP is the main economic component of US President Barack Obama's strategic shift towards the Asia-Pacific.
The alliance of broadly like-minded nations is seen as a counterweight to China, as Beijing expands its sphere of economic and political influence and promotes its way of doing business - seen as often running counter to Western standards.
China's establishment of the Asian Infrastructure Investment Bank (AIIB), which could challenge Western-controlled institutions such as the International Monetary Fund (IMF) that currently set trading rules, has added a sense of urgency.
4. The TPP also comes as global free trade talks move painstakingly slowly at the World Trade Organisation (WTO), which requires unanimous agreements and where negotiations often run foul of conflicting interests between mature economies and emerging nations.
5. Critics, however, say the TPP will mainly benefit big businesses while pressuring small firms and farmers, who will have to compete with cheap foreign imports.
6. The deal still has to be ratified by the parliaments of member nations.
All eyes are on the US Congress, both houses of which are controlled by the generally pro-trade Republican Party.
Its legislators, however, have passionately opposed Mr Obama, a Democrat, on many other issues and the deal could easily get ensnared in 2016 presidential election year campaigning.
Leading candidates to succeed Mr Obama, including Democrat Hillary Clinton, have questioned the TPP in its current form.
In Japan, the second-biggest economy in the bloc, mainstream politicians and economists have generally supported the TPP as positive for Tokyo's export-driven growth even amid concerns over its impact on it prized agriculture industry.
The path to ratification is not likely to be smooth in Australia and New Zealand, with both countries seeing significant debate over the pact.
7. The TPP reduces over time thousands of small and large tariff and non-tariff barriers on trade between members, from Japanese auto parts to the US market, Australian drugs to Peru, US rice to Japan and New Zealand cheese to Canada.
8. The 12 countries must open state procurement further to foreign competition and not give state-owned enterprises undue preference. Also, disputes with foreign investors are to be resolved before expert panels.
9. The TPP establishes five-year to eight-year patent protections for certain kinds of cutting-edge drugs, less than the 12-year US threshold but more than Australia's five years.
10. The TPP sets common standards for the cross-border issues of e-commerce and financial services.
11. The TPP requires countries to live up to the labour rights and fairness standards of the International Labor Organisation.
12. TPP signatories are obliged to make strong efforts towards environmental protection.