请教 OG 105 句子结构

105. An inventory equal to 90 days sales is as much as even the strongest businesses carry, and then only as a way to anticipate higher prices or ensure against shortages.

对整个句子的结构感到迷惑。  ”and then only as a way..."  与第一句的关系是什么呢？  由

and 连接应该是并列， 但是又没有动词。    是 省略句么？

是 An inventory ... is as much as even ...carry, and then only  (as much) as a way...    还是

An inventory ... is as muh as...., and (is) then only as a way...     

可是感觉都不顺阿?

请指教