"He has been exceptionally hostile towards free trade, including notably NAFTA (the North American Free Trade Agreement), and has repeatedly labelled China as a 'currency manipulator'." it said.
"He has also taken an exceptionally right-wing stance on the Middle East and jiadhi terrorism, including, among other things, advocating the killing of families of terrorists and launching a land incursion into Syria to wipe out IS (and acquire its oil)."
By comparison it gave a possible armed clash in the South China Sea an eight - the same as the threat posed by Britain leaving the European Union - and ranked an emerging market debt crisis at 16.
A Trump victory, it said, would at least scupper the Trans-Pacific Partnership between the US and 11 other American and Asian states signed in February, while "his hostile attitude to free trade, and alienation of Mexico and China in particular, could escalate rapidly into a trade war".
"There are risks to this forecast, especially in the event of a terrorist attack on US soil or a sudden economic downturn," it added.
However, the organisation said it did not expect Trump to defeat his most likely Democratic opponent, Hillary Clinton, in an election and pointed out that Congress would likely block some of his more radical proposals if he won November's election.
Rated at 12 alongside the prospect of a Trump presidency was the threat of ISIS, which the EIU said risked ending a five-year bull run on US and European stock markets if terrorist attacks escalated.
The break-up of the eurozone following a Greek exit from the bloc was rated 15, while the prospect of a new "cold war" fuelled by Russian interventions in Ukraine and Syria was put at 16.
The threat list
• China experiences a hard landing
• Russia's interventions in Ukraine and Syria precede a new "cold war"
• Currency volatility culminates in an emerging markets corporate debt crisis
• Beset by external and internal pressures, the EU begins to fracture
• "Grexit" is followed by a euro zone break-up
• Donald Trump wins the US presidential election
• The rising threat of jihadi terrorism destabilises the global economy
• The UK votes to leave the EU
• Chinese expansionism prompts a clash of arms in the South China Sea
• A collapse in investment in the oil sector prompts a future oil price shock
- Daily Mail