In 1952, Harry Markowitz published a short paper that changed how investors think about portfolios.

His insight was straightforward: an asset cannot be judged on its own. What matters is how it behaves alongside everything else you own.

Before Markowitz, diversification was mostly common sense. Own different assets. Don’t put everything in one place.

Markowitz turned that intuition into a framework.

The important variables were expected return, risk, and the relationship between assets. Once you think about a portfolio this way, an asset with a mediocre return can still be useful if it behaves differently from the rest of the portfolio.

That is the basic idea behind Modern Portfolio Theory.

Risk belongs to the portfolio

Suppose you own two assets.

Asset A is relatively volatile. Asset B is also relatively volatile.

It does not follow that the portfolio is necessarily highly volatile.

If the two assets tend to move differently, gains in one can offset losses in the other. The portfolio can therefore have less risk than you would expect from looking at either asset separately.

This is why diversification is about more than counting positions.

Owning ten assets that all respond to the same underlying risk can leave you with something that behaves like one large position.

Owning fewer assets with genuinely different behavior can produce a better-balanced portfolio.

Correlation matters

The relationship between assets is usually described with correlation.

A correlation close to 1 means two assets tend to move together.

A correlation close to 0 means their movements are less related.

A negative correlation means they have historically tended to move in opposite directions.

Correlation is not a guarantee. Relationships can change, especially during periods of market stress.

But it gives investors a way to think about a question that simple asset lists cannot answer:

What happens when I own these things together?

That is the real diversification question.

A simple example

Imagine two assets with the same expected return.

If they are highly correlated, putting them together may add little diversification.

If they have a lower correlation, the same amount of capital can produce a portfolio with a different risk profile.

The point is not that one asset is “safe” and the other is “risky.”

The point is that the combination matters.

Why this matters for Radial

Radial is built around the idea that portfolio construction matters as much as the return of any individual strategy.

Different return sources can have different risk drivers, liquidity characteristics, and market behavior.

The goal is not to collect the highest advertised yield.

It is to think about what those return sources are doing together.

That is the part of portfolio theory that remains useful more than seventy years after Markowitz published his paper.