The most remarkable thing that happened to the world economy after 9/11 was.nothing. What would have once meant a crippling shock to the system was absorbed astonishingly quickly, partly due to the efforts of the then ch...The most remarkable thing that happened to the world economy after 9/11 was.nothing. What would have once meant a crippling shock to the system was absorbed astonishingly quickly, partly due to the efforts of the then chairman of the federal reserve board, Alan Greenspan.