first post so if I write something silly don't hold it against me.
I calculated beta for almost all the stocks that compose the FTSE100. All have beta < 1. This, as far as I understand it, means that they are all less volatile than the benchmark index.
But, how can it be? Shouldn't some of the stocks that compose the index be more volatile??
I downloaded 1 year long historical data for FTSE100 and for several stocks.
I calculated the daily movements (% returns) with the formula:
(close_price_today - close_price_yesterday) /close_price_yesterday
for each day except the last naturally. Did the same for both FTSE100 and all the stocks.
Then used slope function using FTSE100 using:
=SLOPE(array%ret_stock , array%ret_FTSE100)
the values are all above 0 and all below 1 (highest is approximately 0.6)
Here is a sample of what I did: https://docs.zoho.com/file/egrja03b89e74f3ca4dac91e8a02b0d950156