01 · Introduction
Why look at relationships, not individual holdings
Harry Markowitz's insight that earned him the 1990 Nobel Prize in Economics is surprisingly simple. Don't ask which stock is good; ask how stocks move together. If one falls when another rises, holding both together reduces risk on its own — without giving up return.
Your analysis result dissects your portfolio from exactly this perspective. Volatility, Sharpe ratio, the efficient frontier, correlations — all of them are tools derived from that single line of insight.
"The risk of an individual security has no meaning on its own.
What matters is its contribution to the whole portfolio."
— Harry Markowitz, Portfolio Selection (1952)