I would also think that no Anne Hathaway news should result in no positive price changes for a correlation to exist
That's not correct. Imagine the stock price can be derived from two factors A and B such that price = A + B. A is correlated with the price, but a positive price change could also happen caused by B. So no change in A does not guarantee no change in price. And in the case of BRK.A there would be many such factors.
That's not correct. Imagine the stock price can be derived from two factors A and B such that price = A + B. A is correlated with the price, but a positive price change could also happen caused by B. So no change in A does not guarantee no change in price. And in the case of BRK.A there would be many such factors.