Portfolio construction — running several systems — The Professional Layer

One system is a job. Several is a business.

A trader with one system has a single point of failure. When its conditions disappear — and they will — income goes to zero and stays there until the regime turns.

The professional structure is several uncorrelated systems, each small, sized so that no single one can end you. That is portfolio construction, and it is the last technical skill in this curriculum.

One warning first: this is the final step, not an early one. A second system before the first has 300 trades of verified expectancy is not diversification. It is two half-tested systems and no knowledge.

The condition that makes it work

Diversification only helps if the systems are genuinely uncorrelated.

Two trend-following systems on EURUSD and GBPUSD are one system. They will have their good months together and their drawdowns together, and combining them buys you nothing except the illusion of spread risk.

Genuine independence comes from depending on different conditions:

Trend, 4H, EURUSD	Trend, 4H, GBPUSD	Heavily — same edge, same regime
Trend, 4H, gold	Mean-reversion, 1H, EURUSD	Low — one needs trend, one needs range
Breakout, daily	Range fade, 15m	Low, often negative

Limit	Typical	Prevents
Per trade	0.5–1%	One bad trade
Per currency	3%	One view, several tickets
Per system	4% open	One system's bad day
Total open	6%	One bad session across everything
Portfolio drawdown	15%	Everything correlating at once

	Expectancy	Worst drawdown
Gold trend alone	+0.29R	14%
EURUSD range alone	+0.22R	11%
Both, half size each	+0.255R	8%

Portfolio construction — running several systems

One system is a job. Several is a business.

The condition that makes it work

Allocating

The portfolio risk limits

Adding a system without damaging the one that works

Worked example

What to take away