Was concentrated big business behind the Nazi rise?

No, there isn’t much evidence for that now-common claim:

As I show below, the claim that big business contributed to the rise of the Nazi Party is simply inconsistent with the consensus among German historians. While there is some evidence industrial concentration contributed in Hitler’s ability to consolidate power after he was appointed chancellor in 1933, there is no evidence monopolists financed Hitler’s rise to power, and ample evidence showing industry leaders opposed his ascent.

Here is the longer essay, with much more additional detail, from the soon-to-be-better-known Alec Stapp.