The Holy Grail of Diversification, from Kim Zussman
Japan stock index etf EWJ weekly returns were compared with contemporaneous weekly returns for SPY, 1996-present. Correlation between the two returns series were noted at the end of each non-overlapping 10-week period, and this was regressed against date:
The regression equation is corr 10 = - 3.53 + 0.000107 Date
Predictor Coef SE Coef T P
Constant -3.5324 0.8395 -4.21 0.000
Date 0.000107 0.00002223 4.79 0.000
S = 0.274960 R-Sq = 24.7% R-Sq(adj) = 23.6%
The highly significant positive slope coefficient shows the correlation increasing over the past 14 year period.
Relatedly, cartoons have become less correlated with reality over time.