The Stocks Future Price Scenario Lab is an interactive Monte Carlo simulation tool that models thousands of potential future stock price paths using real historical data fetched automatically through your Alpha Vantage API key. By estimating drift and volatility from adjusted closing prices and applying a Geometric Brownian Motion model, it generates a fan chart showing percentile bands, median projections, and the probability that a stock will rise over your chosen time horizon. Rather than predicting the market, it visualizes a statistically grounded range of plausible outcomes, helping traders, investors, and analysts understand uncertainty, evaluate risk, and explore how volatility shapes future price scenarios in a clear, intuitive way.

Stocks Future Price Scenario Lab

Monte Carlo simulation of future stock prices using premium Alpha Vantage adjusted daily data.

Alpha Vantage API Key

Ticker Symbol

Number of Paths

Horizon (Trading Days)

 

Scenario Summary

How to Use the Stocks Future Price Scenario Lab

1. Enter your Alpha Vantage API key

Paste your API key into the API Key field. This allows the tool to automatically download real historical stock prices.

2. Type in a stock symbol

Enter any valid ticker such as AAPL, MSFT, TSLA, NVDA, or AMZN.

3. Fetch historical data

Click “Fetch Historical Data (Alpha Vantage)”. The tool will automatically:

• Download full historical adjusted closing prices

• Fill the history box

• Estimate drift (μ) and volatility (σ) from log‑returns

• Update the current spot price

• Set the chart label to the stock symbol

4. Adjust assumptions (optional)

You can manually change:

• μ (drift) — expected annual return

• σ (volatility) — annualized volatility This is useful for testing bullish, bearish, or high‑volatility scenarios.

5. Set your simulation parameters

Choose:

• Horizon (days) — how far into the future to simulate

• Paths — number of Monte Carlo simulations (e.g., 500–2000)

6. Run the simulation

Click “Run Price Scenarios” to generate:

• A fan chart showing percentile bands over time

• Median projected price

• 10th–90th percentile range at the horizon

• Probability the stock ends higher than today

📊 How to Interpret the Results

Fan Chart (Percentile Bands)

The chart shows a cone‑shaped spread of possible future prices:

• Median line (50th percentile) — the central tendency of all simulations

• 25th–75th percentiles — the middle “normal” range

• 10th–90th percentiles — extreme but plausible outcomes

A wider cone means higher uncertainty or volatility.

Median Price at Horizon

This is the midpoint of all simulated final prices. It’s not a prediction, but a statistical center of the distribution.

10th–90th Percentile Range

This shows the range where 80% of simulated outcomes landed. It helps you understand:

• Worst‑case plausible scenarios

• Best‑case plausible scenarios

• How wide the uncertainty band is

Probability Price > Current

This tells you how often the simulated paths ended above today’s price. It gives a directional bias based on historical volatility and drift.

Overall Interpretation

The tool doesn’t forecast the future—it visualizes risk, uncertainty, and volatility. It helps you answer questions like:

• “How wide could the price realistically swing?”

• “What’s the probability this stock ends higher?”

• “What does the distribution of outcomes look like?”

• “How sensitive is the future to volatility?”

It’s a scenario engine, not a crystal ball—perfect for traders and investors who want to think probabilistically rather than emotionally.