In the context of the input sentence, determine the relationship between 'Warren Buffett' and 'Berkshire Hathaway'.
Options: owner of, employer, brand, product/material produced

It should come as no surprise that the most popular of these portfolios is that of renowned investor Warren Buffett , CEO of Berkshire Hathaway ( BRK.B ) and one of the richest people in the world.
owner of