Choosing Index Funds & ETFs with AI
Index funds and ETFs are the building blocks of a sensible beginner portfolio. There are thousands of them, but you only need 1–3. This lesson teaches you how to use AI to filter the universe down to the right fund for you, evaluate its quality, and avoid the marketing traps that lure beginners into bad choices.
What You'll Learn
- The five criteria that matter when comparing index funds
- A repeatable AI prompt for evaluating any fund
- Why "broad and boring" beats "narrow and exciting"
- How to read a fund factsheet in 5 minutes with Claude
The Five Criteria That Matter
When comparing two similar funds, beginners get lost in marketing. AI helps you focus on what actually moves the needle.
1. Expense ratio. The annual fee, expressed as a percentage of your investment. Good index funds charge 0.03–0.20%. Active mutual funds charge 0.5–1.5%. As we calculated earlier, the difference is enormous over decades.
2. Index tracked. A fund's expense ratio is meaningless without context — what is it tracking? S&P 500? Total US market? Total world? Emerging markets? Two cheap funds tracking different indices give wildly different experiences.
3. AUM (assets under management). How much money is in the fund? Larger funds (€1B+ AUM) are less likely to be closed or merged, have tighter bid-ask spreads, and signal that institutions trust them. For beginners, prefer funds with €1B+ AUM unless there is a strong reason otherwise.
4. Tracking error. How closely does the fund actually match its index? Good index funds have tracking errors under 0.10% per year. Higher means the fund is leaking returns.
5. Domicile and tax treatment. Especially important outside the US. An Ireland-domiciled UCITS ETF and a US-domiciled ETF are taxed very differently in many countries. Beginners in Europe almost always want Ireland-domiciled UCITS ETFs.
The "Evaluate Any Fund" Prompt
Save this in your notebook. Paste it into Perplexity whenever you are considering a fund:
Evaluate [fund name and ticker] as a long-term holding for a beginner investor in [country]. Provide: (1) expense ratio, (2) the index it tracks and what that includes, (3) AUM, (4) inception date and longest available track record, (5) domicile, (6) any tracking error data, (7) top 10 holdings as % of fund, (8) dividend yield and payment frequency. Cite the fund provider's official factsheet for each data point.
You will get a clean profile of any fund in under a minute, with sources you can verify.
Now run it again in Claude to interpret:
Here is the profile of [fund]: [paste Perplexity answer]. Now tell me, for a beginner with a 40-year horizon: what does this fund do well, what are the trade-offs, and what would I miss vs holding a broader fund like [comparison]?
Two prompts, five minutes, and you understand the fund better than 99% of retail investors.
Broad and Boring Beats Narrow and Exciting
Marketing pushes "thematic" or "smart beta" ETFs at beginners. AI ETFs, robotics ETFs, ESG ETFs, dividend ETFs, "high yield" ETFs, "innovation" ETFs. They sound exciting. They are usually:
- More expensive (0.40–0.95% vs 0.03–0.10%)
- More concentrated (50 holdings vs 4,000)
- More volatile
- And, over long periods, lower-returning than the broad market
The boring broad-market funds (total US stock, total world, S&P 500, total bond) win on every meaningful long-term metric for beginners.
Ask ChatGPT:
Compare the expected long-term performance and cost profile of a broad total-world ETF vs three popular thematic ETFs of your choice. Use realistic data and explain why broad funds tend to beat thematic funds over long periods.
You will get a clean argument with examples (often citing ARKK, the famous "innovation" ETF that underperformed the S&P 500 by a wide margin over 5 years).
A Worked Comparison: VTI vs Thematic
Suppose a friend tells you to buy ARKK (ARK Innovation ETF) because "it owns the future." Let's check.
In Perplexity:
Compare ARKK and VTI on: expense ratio, AUM, top 10 holdings, 5-year and 10-year average annual return. Cite Morningstar or the official provider.
You will see something like:
- VTI: expense ratio 0.03%, ~$1.7T AUM, ~4,000 holdings, 10-year return ~12%/yr
- ARKK: expense ratio 0.75%, much smaller AUM, ~30 holdings, 10-year return well below VTI
That settles it. The "exciting" pick lost to the boring one. Hand on heart — the boring one wins this comparison most of the time, across categories.
Reading a Fund Factsheet with Claude
Every fund publishes a one- or two-page factsheet. Download it (PDF), upload to Claude, and prompt:
Read this fund factsheet. Tell me in plain English: (1) what the fund does, (2) the top three things a beginner should know, (3) the three things the fund is not (common misunderstandings), (4) any red flags.
You will get a beginner-friendly summary in seconds. Do this for every fund you consider — and for the funds you already own.
Geographic Tilt
A common beginner question: "Should my portfolio be all US, or should I include international?" The honest answer is "no one knows for sure, but here are the arguments."
Ask Claude:
What are the arguments for and against tilting heavily toward US stocks vs holding a market-weighted global portfolio? Cite the major academic and practitioner viewpoints. Don't tell me which to choose — show me the trade-off.
You will get arguments on both sides:
- Pro US-tilt: historical outperformance, currency familiarity, large innovative companies
- Pro global: diversification, recency bias warning, US-heavy already (~60% of global stock market)
For most beginners outside the US, a global market-weighted approach removes the question entirely. For US beginners, "70% US / 30% international" or "100% target-date fund (which holds both)" are both reasonable.
Bonds: Boring on Purpose
Bond funds get overlooked by beginners because they are dull. Two things to know:
- For young investors with long horizons, a small or zero bond allocation is fine.
- When you do hold bonds, hold a total or aggregate bond index ETF, not a specialty fund.
Use Perplexity:
What is a sensible total bond market ETF for a [country] resident wanting USD/EUR/GBP exposure? Compare two options on expense ratio, duration, credit quality. Cite official sources.
Good enough is BND (US), VAGP/AGGG (UK/Europe), VAB.TO (Canada). One simple fund covers it.
Avoiding Fund Bloat
It is tempting to keep adding funds — small-cap, REITs, gold, emerging markets, commodities, momentum, value. Beginners almost always overdo it.
A good test: every quarter, ask Claude:
Audit my current portfolio: [paste holdings and weights]. Identify any holding that is (1) under 5% of the portfolio (too small to matter), (2) overlapping >50% with another holding, (3) costing >0.30% expense ratio. Recommend simplifications.
Treat the audit as a forcing function to simplify, not a license to add more funds.
Key Takeaways
- Five criteria matter when comparing funds: expense ratio, index tracked, AUM, tracking error, domicile/tax treatment.
- Use Perplexity to profile any fund objectively; use Claude to interpret the profile.
- Broad and boring (total market, total world, S&P 500) consistently beats narrow and exciting (thematic, leveraged, "smart beta") for beginners.
- Read every fund factsheet through Claude before holding the fund.
- Audit your portfolio quarterly and prune anything too small, redundant, or expensive.