<sod >The share prices of the UK's big housebuilding firms have fallen hardÂ since the referendum result, with Berkeley Group this week relegated from the FTSE 100 bluechip index due to the steep decline in its market value.< eod>< sod > The share prices of the UK's big four housebuilding firms have fallen hard since the referendum result, with Berkeley Group this week relegated from the FTSE 100 bluechip index due to the steep decline in its market value.< eod>