This is kind of funny, but the explanation sounds logical.... https://www.huffingtonpost.com/dan-mirvish/the-hathaway-effect-how-a_b_830041.html "When Anne Hathaway makes headlines, the stock for Warren Buffett’s Berkshire-Hathaway goes up. Think of Berkshire-Hathaway shares (BRK.A) as a really expensive version of the IMDb’s StarMeter (which actually is designed to go up and down as actors make the news). But a bedrock member of the New York Stock Exchange? The evidence would indicate as much. Oct. 3, 2008 - Rachel Getting Married opens: BRK.A up .44% Jan. 5, 2009 - Bride Wars opens: BRK.A up 2.61% Feb. 8, 2010 - Valentine’s Day opens: BRK.A up 1.01% March 5, 2010 - Alice in Wonderland opens: BRK.A up .74% Nov. 24, 2010 - Love and Other Drugs opens: BRK.A up 1.62% Nov. 29, 2010 - Anne announced as co-host of the Oscars: BRK.A up .25% My guess is that all those automated, robotic trading programming are picking up the same chatter on the internet about “Hathaway” as the IMDb’s StarMeter, and they’re applying it to the stock market. "
Perhaps. Most likely spurious correlation. Correlation does not imply causality! The entire market has been moving up since the bottom in 2008/2009. You can arrive the same conclusion with other stocks too. Not just BRK.
That's true and it is the future of investing. It is called Data Mining. Logically unknown factors showing correlation and there kicks in the BUY or SELL signal. Something like modification or advancement of January effect logic that "as goes Januray so does the rest of the year". Just like HFT, those who have faster and higher computing power will hold the advantage.