<disclaimer: the idea for this post came from a tweet, but I am sorry I can’t find it to credit>
The unfound tweet above probably linked back to an article I did not read, but it gave me the idea of checking out how much of the daily volume of shares traded on any of the stock exchanges was tagged to a single ticker. Predictably, I could not find any which accounted for more than 1.5% of total average daily volume.
When you calculate the ratio to traded value, however, the picture changes – I used the latest daily value traded stats for April (around USD80bn per day, up around 30%) and Apple accounts for around 18% of NASDAQ, while Berkshire Hathaway accounts for nearly 8.5% of the Big Board.
I am not sure what it means when a stock becomes a proxy for a whole market, but it sure tells you something about the influence it has on it.