The correlation coefficient over this time period is 0.71, very high.
I show this chart with tongue firmly planted in cheek. I'm not a huge fan of analog charts and off hand I know of no apparent reason why this relationship should exist. Always keep in mind the old adage, "correlation does not imply causation."
But perhaps there is a fundamental, logical reason(s) for AAPL & GLD to trade roughly in-synch (a strong/weak USD?), let me know your thoughts.
Happy Labor Day!