Is a comma required after "IBM" in the following sentence?
His speech focused on his time working for IBM and cultural
differences between America and Brazil.
I know a comma must come before a conjunction if it separates two independent clauses, and "cultural differences between America and Japan" isn't an independent clause. (right?) That said, it seems almost to be a run-on sentence to me without a comma. Thus I am confused.
There is no need for a comma here. This is a list of two items, one of which is a list of two items. That said, if you think a comma makes it clearer, then you could use it. It's your choice. It's definitely not a run-on sentence.