Correlation
Correlation measures, between −1 and +1, how far two assets move together. Near +1 they rise and fall in step; near −1 they offset each other; near 0 they are independent. It is the basis of diversification, with one important caveat: in a crisis correlations tend to shoot towards 1, precisely when you most needed them not to.
See also
See it on real data
Celsmar computes this from the accounts companies file with their regulator, and shows which line every figure comes from. Free to start, no card.
Definition for informational purposes. It is not financial advice nor a recommendation to buy or sell.