Question

The beatles' most important collective investment was __________, the company that controlled their share of any film projects and promotional films for tv.

Answer 1

The beatles' most important collective investement was Subafilms, the company that controlled their share of any film project and promotional films for TV. The Beatles were an English rock band which was founded in Liverpool in 1960 by four men. They are regarded as the most influential act of the rock era.
The beatles own Subafilms; they also have shares in Northern Songs Music Publishing, which was the company that holds the publishing right to their songs. 

Answer 2

the beatles' most important collective investment was subafilms

Subafilms is a company that created both the beatles animation films and selling the beatles' merchandising products at the same times.
The sales made from these products, massively increased the wealth of each the battle's members.