So far this year they have invested nearly $1.2bn in the industry, nearly half as much again as the annual record in 2019 (see chart).

half 是副词，可归类于倍数副词，用来修饰比较结构，作程度状语。

half as much again as 属于倍数表达。副词again 表示在much 这个量的基础上“增加了一倍”，half 指“一半”，就是“增加了一倍的一半”。所以， half as much again as 实际意思是：“在原来的数量上增加了一半”。也就是原来数量的一倍半，据此可以推算出2019年的投资额是 $ 0.8 bn。

如果去掉 half ，as much again as 表示纯的“增加了一倍”，“是原来的两倍”。例如：

This fountain pen cost me as much again as the one I bought last time. 这支钢笔比我上次买的贵一倍（是两倍的价格）。