Look-through: how Portfolio Lab sees inside funds

In depth6 min read · updated 24 October 2026 · 2 sources

The look-through looks through the funds to the securities they contain. This methodology describes where the holdings lists come from, how Portfolio Lab reads and standardises them, how countries, sectors and individual securities are added up across all funds, and how each position finds its place in the asset class taxonomy. The benefits are explained in the article Look-through.

Where the holdings come from

For each fund in the grid, Portfolio Lab tries the sources in a fixed order: first your own file or link (CSV or Excel, as fund companies offer them under “all holdings”), then the holdings files of large ETF providers, which can be found via the ISIN. If that fails, what remains is the largest holdings and the breakdown by sector and asset class from a market data service, but without countries and without a complete list.

• Individual stocks represent themselves; sector and country come from the securities database.
• Asset classes (@ tickers) show the holdings of their fund section or count as a single position (bonds, money market, gold).
• Commodity ETCs count as a single position in the commodities sector, without country exposure.
• Stored lists are considered out of date after 35 days; an admin can reload them with “Refresh”.

Reading and standardising files

Holdings files look different at every provider. The parser finds the header row itself (German or English), recognises CSV or Excel, a comma or a point as the decimal separator, and percentages or fractions. Total rows (“Total”, “Gesamt”) are dropped. The fields are then standardised:

• Countries to German names and ISO codes, grouped into six regions: North America, euro area, Europe ex euro area, Pacific (developed), emerging markets, other.
• Sectors to the eleven sectors of the GICS classification (information technology to real estate).
• Asset classes to equities, bonds, cash, derivatives and commodities. Cash, margin and FX forwards are given the sector “Cash/derivatives” and “No country exposure”.
• Bond data, where available: duration, maturity, coupon and yield as the basis for the risk factors.

A list counts as complete if its weights add up to at least 90% and it does not just contain the largest holdings.

Breakdown by country and sector

For each fund, a breakdown summing to 100% is created first. If the list is complete and at least half of the weight carries the information (a country, for example), the weights are added up per country and divided by the total; positions without the information are labelled “Unassigned”. Otherwise Portfolio Lab uses a ready-made breakdown from the data service and, if that does not exist either, the known holdings plus “Other positions” for the remainder. Without any data, the whole fund appears under “No data”. Nothing is made up.

Individual securities and concentration

For the list of the largest individual securities, all holdings except cash and derivatives are merged across all funds. The same stock is named slightly differently in every file (“APPLE INC”, “Apple Inc.”) and does not always have an ISIN. Portfolio Lab therefore links holdings in two passes, via the ISIN and via a cleaned-up name without legal-form suffixes; this way, the result does not depend on the order of the funds. Positions counted as a whole (asset classes, commodities) do not count as individual securities.

In addition, the page shows the share of the ten largest securities and the coverage: which part of the portfolio is fully, partly or not at all looked through. The look-through measures the actual composition from the holdings, in contrast to the returns-based style analysis following Sharpe (1992). Benchmarks built on holdings characteristics were developed by Daniel et al. (1997) to measure fund performance.

Taxonomy: every position in its place

The taxonomy classifies the portfolio along three separate dimensions: asset class (what you own; 13 categories with main and subcategories), risk drivers (what generates return and risk; one primary and several secondary drivers per subcategory) and instrument and strategy (individual security, ETF, ETC, fund, future; passive, factor, active, leveraged …). Size, style, maturity and rating are attributes that cut across these dimensions.

1. A custom assignment that an admin has stored for a security.
2. The asset class assignment for @ tickers.
3. Rules based on name, type and category (money market, crypto, volatility, option strategies, leveraged products, REITs, infrastructure, commodity types, bond types with currency, maturity and rating).
4. Breakdown via the holdings list: equities by country (euro area core: Germany, France, the Netherlands, Belgium, Austria, Finland, Luxembourg; periphery: Italy, Spain, Portugal, Greece, Ireland and the other euro countries; emerging and frontier markets separately), government bonds by issuer country, cash as liquidity within the fund.

Funds that track a special category (REITs, infrastructure, private equity, commodities) count as a whole, even if their holdings list consists of stocks. If only part of the list is known, the rest receives the fund's classification.

Limitations

• Holdings lists are snapshots as of a reference date; the fund changes between two retrievals.
• Derivatives, swaps and synthetic replication only appear as the provider reports them.
• Where only the largest holdings are known, a remainder stays undetermined. The coverage shows how large it is.

This page describes how Portfolio Lab calculates; past results are not a forecast. All terms in the glossary.