From Wiki regarding significance of this index Financial[edit] The geometric mean has from time to time been used to calculate financial indices (the averaging is over the components of the index). For example, in the past the FT 30 index used a geometric mean.[10] It is also used in the recently introduced "RPIJ" measure of inflation in the United Kingdom and elsewhere in the European Union. This has the effect of understating movements in the index compared to using the arithmetic mean.[10] 4/20/16
Thanks. I was not aware of this index. a .618 retraction would be around 468. and its at the 200 day average so I wouldn't be surprised the next down move soon start. 4/21/16