How do stock-market investors even begin to calculate the impact of an entirely different global political hierarchy, a system where decades-old alliances appear to have fallen by the wayside and former allies begin to look more like competitors and rivals? This is the extreme worst-case scenario that Wall Street analysts have begun to consider over the past couple of weeks, as President Donald Trump has repeatedly assailed allies and cast doubt on the usefulness of alliances like the North Atlantic Treaty Organization. Market watchers have said that the prospect of any fundamental changes to key alliances would be extremely unlikely — both because it would be difficult to exit an alliance like NATO, and because such a move would undoubtedly face extreme and widespread resistance — but recent events have put the outcome in view in a way that would have seemed unthinkable just a month ago.via