The Japanese author Kenichi Ohmae wrote in his 2006 bestseller The M-Shaped Society that the shifting of income distribution so that the left and right ends of the spectrum are rising, while the middle is falling (thereby creating an M-shaped society), is a global phenomenon.
日本作家大前研一在 2006 年初出版的暢銷書《Ｍ型社會──中產階級消失的危機與商機》即指出，所得階層的分布出現位移，邁向左右兩端高峰、中間崩落的「M 型社會」，已經是全球趨勢。