> ## Documentation Index
> Fetch the complete documentation index at: https://docs.driven.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Build a Portfolio

> How to build a paper portfolio from scratch in Driven: translate a strategy into positions, size them with rules, and construct a diversified set of holdings.

This guide covers building a paper portfolio from scratch, going from a strategy to an actual set of positions. Whether you are testing a new approach or modeling a real allocation, Driven can help you translate a strategy into sized, diversified holdings.

The concept behind this is [Portfolio and Paper Trading](/concepts/portfolio-and-paper-trading), and it works best when your [Playbook](/concepts/playbook) holds your sizing rules.

## When to use this

* Starting a paper portfolio to test a strategy
* Modeling an allocation before committing real capital
* Building a diversified set of positions around a thesis

## Step 1: Define the strategy and constraints

Before buying anything, state what the portfolio is for and the rules it follows:

```text theme={null}
I want to build a paper portfolio of US large-cap quality companies. Maximum 10% per position, at least 8 names, diversified across sectors. Suggest a starting portfolio with the rationale for each holding.
```

If your [Playbook](/concepts/playbook) already holds your sizing and risk rules, the Agent will apply them automatically.

## Step 2: Review the proposed construction

Look at the whole before placing trades:

```text theme={null}
Before I build this, show me the proposed sector allocation and concentration, and flag any risks in the construction.
```

## Step 3: Build it

Once you are happy with the plan:

```text theme={null}
Build this portfolio in my paper account using the weights we discussed.
```

The Agent places the trades and the positions appear in the portfolio.

## Step 4: Document the thesis

Capture why you built it this way, so you can judge it later:

```text theme={null}
Summarize the thesis for this portfolio and the one metric to watch for each holding. Save it as a file.
```

## Step 5: Set up monitoring

A portfolio you do not watch drifts. Schedule a review:

```text theme={null}
Each week, review this portfolio's performance and flag any holding that has moved away from its thesis.
```

See [Portfolio health check](/guides/portfolio/portfolio-health-check) and [scheduled tasks](/concepts/scheduled-tasks).

## Common mistakes

* **Building without rules.** A portfolio with no sizing or diversification rules tends to become concentrated by accident. Set the constraints first.
* **Ignoring sector overlap.** Eight names in the same sector is not diversified. Check the sector allocation.
* **No thesis on record.** If you do not write down why you bought, you cannot tell later whether the thesis broke or just the price moved.

## Related

* [Place a paper trade](/guides/portfolio/place-a-paper-trade) — the mechanics of trading
* [Portfolio health check](/guides/portfolio/portfolio-health-check) — review the portfolio
* [Build your Playbook](/guides/strategy/build-your-playbook) — where sizing rules live
* [Paper trading prompts](/prompts/paper-trading-prompts) — more templates