03 - Portfolio Risk

Portfolio risk

Before you add to a position, see how much you could lose.

BLS Prime tests the positions you own against severe market scenarios and shows the loss, the weak spots, and the positions responsible.

Try the example portfolioRead methodology

Research software. Not financial advice.

Public lab · working engine

Edit a portfolio and see where it breaks.

Change the weights, add a company, and run the same scenario engine used by the private workspace. This is an editable example portfolio; the results are not a canned demo.

What you get

What happens when you run the review

You do not need to understand financial models. The review answers one practical question: if markets fall sharply, where does this portfolio hurt?

01Add holdingsEnter tickers and weights once. Cash and unmatched tickers stay visible instead of being hidden.
02Test difficult marketsThe review applies severe but plausible market moves to the positions it can match.
03Read where it hurtsYou see the loss in a bad scenario and which positions explain it.

If the next 30 days go badly, how much does the portfolio lose?

CVaR 5%Average loss in the most severe scenarios

How often do simulated scenarios finish below zero?

Loss shareShare of scenarios with a loss

Which positions hurt most when the bad scenarios arrive?

Risk driversPositions that explain the loss

Can a reviewer reproduce this exact run later?

Run recordDetails saved for review

How to read it

A reference for studying difficult markets.

The calculation uses historical market relationships and severe scenarios. It is a way to understand exposure, not a forecast of the next market move.

Checks against past market drops

We compare the size of the simulated loss with several historical episodes:

Pre-2020 COVID checkReal drop -33.3%Stress q01 -36.9%Pass

Pre-2022 inflation checkReal drop -13.5%Stress q01 -41.7%Pass

Pre-2023 rate stress checkReal drop -6.8%Stress q01 -42.0%Pass

This is a comparison with past episodes, not a claim that the calculation can reproduce every crisis.

How it is calculated

The short version

The review uses historical market relationships and applies difficult market conditions to the holdings it can match. If coverage is incomplete, the page shows the gap instead of pretending the portfolio is complete. Each run keeps its inputs and date for later review.

What it cannot do

It does not tell you what will happen next. It shows how your current portfolio behaves in difficult simulated markets.
It is not a day-by-day market forecast.
Some tickers may not have enough matching history. When that happens, the page shows the gap instead of hiding it.
The headline loss is deliberately severe. It describes a difficult scenario, not the most likely market case.
It is analysis software, not advice, not a trade instruction, and not a replacement for human judgment.

Review your actual holdings.

Open the workspace, choose the type of market you want to examine, and review the portfolio you own.