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How to Prepare NAV Data

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Preparing your data is the first step to running drawdown analysis. Here is the step-by-step process to validate your files and save them locally in your browser.

Prepare your NAV file

Create a text file (CSV, TSV, TXT) or an Excel spreadsheet (XLSX, XLS) containing your historical data:

  • One column for the period dates (daily, weekly, or monthly)
  • One column for the NAV (or closing price, equity curve level)

Your rows can be in any date order (ascending, descending, or unsorted) as the browser automatically sorts them chronologically before saving, but they must contain no duplicate dates.

Check your column names

PortBlend uses automatic header matching to detect your columns. Ensure your headers match one of our accepted aliases:

  • Date aliases: date, date_time, tradedate, trade_date, datetime, timestamp, period, week, month, observation_date, nav_date, nav date
  • NAV aliases: nav, nav_value, equity, cum_nav, cumnav, cumulative_nav, close, value, portfolio_value

If your spreadsheet uses other headers and has more than 2 columns, you can map them interactively during upload.

Validate and save locally

  1. Go to the Prepare Data tab in the PortBlend app.
  2. Drag your file directly into the drop zone, or click Browse files to select it from your device.
  3. The files will appear under the drop zone with a real-time status badge:
    • Ready: Columns and date formats were auto-detected successfully.
    • Needs Mapping: The file is ambiguous (e.g. contains multiple date columns, or custom headers). Click Map Columns next to the file name to open the Format Assistant, select the correct columns and worksheets, and run a live preview validation check.
    • Error: The file is corrupt, has too many rows, or contains invalid characters.
  4. Click the Save [N] ready files button.

PortBlend checks the file before analysis. The validated series is saved in your browser portfolio; the files themselves are never stored on PortBlend servers.

Confirm the series in My Browser Portfolio

After successful validation, your series will appear in My Browser Portfolio.

  • Verify that the row count matches your expectations.
  • The series is now available to select in the Drawdown Dynamics and Portfolio Blending config panels.

To remove any browser-saved series, click the red delete icon on its row.

Where to go next

Once your files are validated and saved locally:

  1. Go to the Drawdown Dynamics tab to run your first single-series drawdown analysis.
  2. Add a second series and configure your first Portfolio Blending analysis to see how combining them changes your portfolio’s risk profile.