Two major “stylized facts”
Changes in U.S. stock prices lead changes in foreign markets. For example: Vanguard Total Intl Stock Idx (VGTSX) d = 0.459 * ^spcd' + -0.0006 r^2 = 0.334 tstat = 11.2
This effect is visible for Europe, Japan, and for emerging markets, and can be explained partly as a time-zone effect. See Correlations and Volatilities of Asynchronous Data by P. Burns, R. Engle, and J. Mezrich, UCSD Economics Discussion Paper 97-30R,
Gold funds show trending behavior. For example: Vanguard Gold & Precious Met (VGPMX) d = 0.339 * VGPMXd' + -0.0011 r^2 = 0.115 tstat = 5.7
Gold fund trending may persist because the market for gold stocks is too illiquid to be of interest to professional traders.