关于market leverage和book leverage的研究可以追溯到Fama和French在1992年的论文The Cross-Section of
Expected Stock Returns（没错就是讲三因子模型的那篇）。

论文里关于两种leverage的定义原话是We use two leverage variables, the ratio of book assets to market equity, A/ME, and the ratio of book assets to book equity, A/BE. We interpret A/ME as a measure of market leverage, while A/BE is a measure of book leverage.

A指的是Total Assets，ME指的是Market Value of Equity，BE指的是Book Value of Equity。Market leverage和book leverage是对公司财务杠杆的两种衡量方式，我们平时一般说的financial leverage指的是book leverage。

顺带一提，论文中的结论是股票收益和market leverage成正相关，和book leverage不相关甚至轻微负相关