Your First Portfolio Blend Analysis
Portfolio BlendingPortfolio BlendingCombining multiple assets, strategies, or return streams into one portfolio to study how the combined result changes risk, drawdown, and consistency. lets you combine two or more NAV seriesNet Asset Value (NAV)A single number that tracks the value of a portfolio, fund, or strategy over time. Formula: NAV_t = NAV_t-1 * (1 + Return_t), assign weightsAllocationThe target percentage assigned to each series in a portfolio blend. Allocations can sum to 100%, or leave a remainder as CASH., choose a rebalancingRebalancingPeriodically resetting portfolio weights back to their target allocation. As assets move, their relative weights drift from your target; rebalancing sells some of the outperforming assets (winners) and buys the underperforming ones to restore your original risk profile. mode, and see how the blend behaved historically.
It is not an optimiser. It does not tell you the best allocation. It shows what happened to the specific blend you entered: the combined return path, the drawdownsDrawdownHow far a portfolio or series has fallen from its historical peak at any point in time, measured as a percentage. Formula: Drawdown = ((Current NAV / Peak NAV) - 1) * 100, and which series drove portfolio stress.
Portfolio Blend Analysis requires a free account. Drawdown Dynamics remains available without an account.
Before you start
For a clean first run, make sure you have:
- A free PortBlend account.
- At least two validated NAV series in My Browser PortfolioMy Browser PortfolioThe browser-saved list of validated NAV series available for analysis. To protect the confidentiality of your proprietary investment strategies and trade data, PortBlend operates as a stateless processor: files are stored locally in your browser storage, and the server processes calculations in-memory without ever saving your files..
- Two quota-eligible series on the free plan (or more on Pro).
- Monthly selected as your first rebalancing mode.
- Contribution and Dominance left enabled.
- Filter Date Range left blank.
This gives you the simplest Portfolio Blend Analysis baseline: the full common overlap, monthly rebalancing, and all core report tabs enabled.
Prepare at least two NAV series
Go to Prepare Data and validate at least two CSV files into My Browser Portfolio.
Each file represents one series (e.g., an equity index, bond fund, gold, managed account, or strategy backtest). If you do not have files ready, use the Load Sample Data (S&P 500 & GOLD) button to populate two test series instantly.
For file specifications, see the NAV file format reference. For a step-by-step upload guide, see How to Prepare NAV Data.
Recommended first run
If you are trying Portfolio Blend Analysis for the first time, start with a simple two-series blend:
| Series | Allocation |
|---|---|
| S&P 500 | 50% |
| GOLD | 50% |
Use the default Monthly rebalancing mode and leave the date filter blank. This equal-weight setup makes the results easy to inspect. Once you understand the output, you can change one parameter at a time.
Sign up or log in
Click Sign Up or Log In in the left sidebar.
If you open Portfolio Blending while unregistered, the page displays the Config panel but replaces the Run button with Sign Up alongside the note: “Portfolio Blend Analysis requires a free account.”
Your saved NAV series are stored locally in your browser via IndexedDB; signing up or logging in will not overwrite or clear your local portfolio.
Open Portfolio Blending & allocate weights
Click Portfolio Blending in the left sidebar. If no analysis exists, the Config panel opens automatically, showing “Select at least 2 series and click Run.”
In the Series Allocation table on the left:
- Enable: Check the checkboxes next to at least two saved series. If fewer than two are checked, the Run button remains disabled with the warning: “Select at least 2 series for Portfolio Blend Analysis.”
- Allocation %: Enter a target weight (0 to 100) for each enabled series. If allocations total less than 100%, the remainder is assigned to CASH (unallocated portfolio weight).
Select rebalancing, options, and dates
On the right side of the Config panel, configure the following:
- Rebalancing Modes: Select how the portfolio resets back to target weights. The default is Monthly (resets weights on the last available trading day of each month). Other options include None (drifting weights), Daily, Weekly, Quarterly, Half-Yearly, and Yearly.
- Options: Leave ContributionContributionThe percentage of a blended portfolio's drawdown episode that was driven by an individual asset or series. and DominanceDominance RatioAn asset's average drawdown contribution divided by its portfolio weight. Ratios above 1.5 indicate disproportionate risk. checked. Leave Weekly heatmap unchecked (off by default) unless your data is high-frequency and you want extra calendar detail.
- Filter Date Range: Leave blank to analyze the full common overlapping date rangeCommon OverlapThe shared date range where all enabled series have data available. Portfolio Blending runs on this overlapping period so every series is compared fairly. where all selected series have data.
Run the analysis
Click Run (the play icon). The button changes to Running… as PortBlend normalises the series to base 100Base 100 NormalizationNormalising the starting value of multiple series to 100 to compare their relative performance on equal footing., builds the combined portfolio, and runs the drawdown, contribution, and dominance engines.
When the run completes, the Config panel collapses into a sticky summary bar, and the report appears below. To adjust weights or settings, click Open on the collapsed Config summary bar, make your changes, and click Run again.
Read the report outputs
The report starts with the common overlapping date range and the active rebalancing mode. Every series is normalised to base 100.0 at the portfolio start datePortfolio Start DateThe first date where every enabled series in a Portfolio Blending run has usable data. PortBlend normalises each series to base 100 on this date. to ensure a fair comparison.
Stats Summary
This table displays the combined portfolio’s performance:
- Rebalance Mode
- Total Return (%) and CAGRCAGR (Compound Annual Growth Rate)The annualised return — the equivalent steady yearly growth rate required for a portfolio to grow from its starting to ending value. Formula: CAGR = ((Ending NAV / Starting NAV) ^ (365.25 / Calendar Days) - 1) * 100 (%)
- Max DrawdownMaximum DrawdownThe deepest peak-to-trough decline recorded in a portfolio or series over a specific period, representing the worst-case historical loss. Formula: Max Drawdown = Min(Drawdown_t) over the series range. (%) and Avg DrawdownAverage DrawdownThe average depth across all historical drawdown episodes. Formula: Avg Drawdown = (Sum of Episode Depths) / (Total Episodes) (%)
- Max DD Duration (days) and Total Episodes
Per-symbol DCD Comparison
This table shows how each individual asset performed over the same timeframe on a normalized base 100.0. The note below reads: “All symbols normalized to base 100.0 at portfolio start date.”
Read the Drawdown tab
Active by default, this tab shows the blended portfolio’s combined drawdown risk:
- Portfolio NAV + Drawdown Timeline: Shows combined NAV (blue) and drawdown (red). Drag on this chart to select a date range.
- Yearly Drawdown Overview: Highlights the deepest drawdown reached in each calendar year.
- Monthly / Weekly Stress Heatmaps: Shows monthly and weekly drawdown stress in calendar views.
- Drawdown Episodes: Displays a table of all historical drawdown episodes in the blended portfolio, sortable by Start, End, Depth, or Duration.
Read the Contribution and Dominance tabs
These two tabs show which assets drive portfolio stress:
- Contribution tab: Shows the percentage of drawdown driven by each series during calendar periods and individual episodes. For example, if a 30% asset allocation is responsible for 60% of a portfolio drawdown episode, it is contributing disproportionate risk.
- Dominance tab: Summarizes risk concentration by calculating the Dominance RatioDominance RatioAn asset's average drawdown contribution divided by its portfolio weight. Ratios above 1.5 indicate disproportionate risk. (average contribution divided by asset weight). If this ratio exceeds 1.5, the status is flagged as WARNING, highlighting assets that dominate portfolio risk.
For a detailed breakdown of these formulas, warning thresholds, and how to act on the data, see the complete guide on Understanding Contribution and Dominance.
Common issues & troubleshooting
Why is Run disabled?
- You have enabled fewer than two series.
- Your total allocation exceeds 100% (lower the Allocation % values until the total is 100% or less).
Why do I see CASH?
If allocations add to less than 100%, PortBlend treats the remainder as CASHCASHUnallocated portfolio weight in a blend. CASH has zero return and zero drawdown, so it acts as a historical cash buffer rather than being scaled into other series.. CASH stays as unallocated portfolio weight with zero returnReturnThe gain or loss of an asset, strategy, or portfolio over a period, usually expressed as a percentage of the starting value. and zero drawdownDrawdownHow far a portfolio or series has fallen from its historical peak at any point in time, measured as a percentage. Formula: Drawdown = ((Current NAV / Peak NAV) - 1) * 100, acting as a buffer.
Why did my start date change?
Portfolio Blending runs on the common overlapCommon OverlapThe shared date range where all enabled series have data available. Portfolio Blending runs on this overlapping period so every series is compared fairly. of all enabled series. The analysis starts on the first date where every enabled series has data.
Why did my NAV values drop/change after filtering?
When you apply a date filter (either manually or by dragging on the chart), PortBlend re-normalizes all enabled series to base 100.0 at the new start date of the filtered range. This resets their starting value to 100.0, which re-scales all subsequent NAV values. This explains why your NAV values may appear to drop or shift suddenly after applying a filter.
Why are Contribution or Dominance tabs disabled?
You did not check Contribution or Dominance in the Config panel before running. Open the Config panel, enable them under Options, and click Run again.
What to do next
After your first run:
- Compare Monthly rebalancing with None to see how periodic resets affect drawdown.
- Add a cash buffer by lowering allocations and observe how CASH reduces maximum drawdown.
- Read the What is correlation in portfolio diversification? blog post to learn the science behind portfolio blending.
Try it yourself with your own data — free account, no credit card required.