Narcis Miclaus

7 min read

Personal finance, from zero Lesson 27 / 60

Stock exchanges and indices

Borsa Italiana, Xetra, Euronext. FTSE MIB, MSCI World, S&P 500. How exchanges work, what indices measure, and how to read ETF names without confusion.

Sofia wants to buy “the S&P 500.” She opens her broker, searches “S&P 500 ETF,” and sees 27 results across three exchanges, in USD and EUR, with different ticker symbols, and she has no idea which to pick.

Today’s lesson is the landscape. Exchanges, indices, tickers, listings — the plumbing that retail investors rarely learn because it’s assumed and never explained.

What an exchange is

A stock exchange is a regulated marketplace where buyers and sellers meet to trade financial instruments. Most trading is electronic now — physical trading floors are mostly ceremonial.

Main European exchanges relevant to Italian retail:

  • Borsa Italiana (Milan) — Italian stocks, ETFs listed in EUR.
  • Xetra (Frankfurt) — German and pan-European stocks, ETFs in EUR.
  • Euronext (Paris, Amsterdam, Lisbon, Brussels) — pan-European stocks, ETFs in EUR.
  • SIX Swiss Exchange (Zurich) — Swiss stocks, some ETFs in CHF.
  • LSE (London) — UK stocks, ETFs in GBP or USD.

An ETF can be listed on multiple exchanges. The same iShares Core MSCI World might trade on Borsa Italiana, Xetra, LSE, and SIX — same underlying fund, different listings.

The difference between listing and domicile

Two distinct concepts often confused:

  • Domicile: where the fund is legally established. Shown by the first two letters of its ISIN. IE = Ireland, LU = Luxembourg, FR = France, DE = Germany, US = USA.
  • Listing: where you can buy/sell the fund shares. An Irish-domiciled ETF can be listed on Borsa Italiana, Xetra, LSE.

For tax purposes, what matters is the domicile (and the fund structure — UCITS or not). For trading convenience, listing matters (affects your transaction fees, the currency of trade).

For Italian retail investors:

  • Irish-domiciled UCITS ETFs are the most common and tax-efficient.
  • Listed on Borsa Italiana in EUR: no FX cost.
  • Listed on Xetra or Euronext in EUR: also fine, sometimes cheaper trading fees.
  • Listed on LSE in USD: adds FX conversion cost to/from EUR at each trade.

Prefer EUR-listed variants when available.

What an index is

An index is a rules-based list of securities, weighted in some way, used as a benchmark.

  • Price index: simple value based on prices of constituents.
  • Total return index: includes reinvested dividends. What ETFs actually track.

Index providers:

  • MSCI (US). MSCI World, MSCI Emerging Markets, MSCI ACWI.
  • FTSE Russell (UK). FTSE All-World, FTSE 100, FTSE MIB (Italian).
  • S&P Dow Jones Indices (US). S&P 500, Dow Jones Industrial Average.
  • STOXX (EU). STOXX Europe 600, Euro STOXX 50.

Each provider has slightly different methodology. MSCI World and FTSE Developed are similar but not identical (different country inclusion rules, different float adjustments).

The main global equity indices

Ordered by scope:

MSCI World

  • 1,500+ large/mid-cap stocks from 23 developed markets.
  • Excludes emerging markets entirely.
  • Weights: market-cap based. US dominates at ~70%.
  • Reconstituted quarterly.

MSCI ACWI (All Country World Index)

  • 2,900+ stocks from 23 developed + 24 emerging markets.
  • Weights: market-cap. US ~63%, emerging markets ~10%.
  • The closest thing to “buy the whole world in one index.”

FTSE All-World

  • 3,800+ stocks from developed + emerging.
  • Slightly different country weightings vs MSCI ACWI.
  • Popular Vanguard ETFs track this.

S&P 500

  • 500 largest US stocks. US-only.
  • Market-cap weighted; dominated by a few giant tech stocks.
  • The benchmark most often cited in US-focused news.

FTSE MIB

  • 40 largest Italian stocks.
  • Market-cap weighted.
  • Dominated by financials, utilities, energy.
  • The Italian equivalent of the S&P 500 (much smaller).

STOXX Europe 600

  • 600 largest European stocks across 17 European countries.
  • Broad European exposure.

Euro STOXX 50

  • 50 largest Eurozone stocks.
  • Narrower than STOXX 600.

Market cap weighting

Most indices weight stocks by market capitalization — the total value of all outstanding shares.

For MSCI World:

  • Apple, Microsoft, Nvidia collectively = ~15% of the index.
  • Tiny companies = tiny weights.

This means an MSCI World tracker naturally concentrates in whatever’s biggest today. In 2000 that was Japanese stocks (Japan was ~20% of index); in 2024 it’s US tech.

Pros: reflects actual market. Low turnover. Self-correcting.

Cons: overweights recent winners. Crashes can disproportionately hurt when the “mega-caps” fall.

Alternative weighting schemes: equal-weight (each stock 1/500 in S&P 500), fundamentally weighted (by earnings or book value), smart beta (various factor-based). All more expensive and historically haven’t consistently beaten simple market-cap.

For most retail investors, market-cap weighted is the default and reasonable choice.

Float adjustment

Important nuance: market cap for index weighting is free-float adjusted. Shares held by insiders, controlling shareholders, or governments don’t count toward the weighting.

Example: Italian state owns ~30% of ENI. The full market cap of ENI is €50B. Float-adjusted for index purposes: ~€35B (the 70% freely tradable).

This makes indices more reflective of what’s actually available to trade.

Reading ETF names

A typical ETF name encodes useful information:

iShares Core MSCI World UCITS ETF USD (Acc)

Decoded:

  • iShares: provider (BlackRock brand).
  • Core: low-cost line.
  • MSCI World: index tracked.
  • UCITS: EU-compliant.
  • ETF: the structure.
  • USD: fund currency (what NAV is denominated in).
  • (Acc): accumulating (reinvests dividends).

Dist variant would be (Dist) or (Inc).

When you buy, the exchange listing might be in a different currency than the fund currency. iShares Core MSCI World USD Acc is listed on Borsa Italiana in EUR, on LSE in USD, on Xetra in EUR. Buying on Borsa Italiana in EUR: you never see the USD, the exchange converts at market rate instantly.

How prices are set

Exchanges run a continuous double auction:

  1. Buyers submit buy orders at various prices.
  2. Sellers submit sell orders at various prices.
  3. The exchange matches compatible orders.
  4. The best bid (highest buyer offer) and best ask (lowest seller offer) define the current spread.
  5. When a market order arrives, it executes at the best available price.

The price you see on your broker is the last trade price or the midpoint of bid-ask. The price you pay if you place a market order is the current best ask (for a buy) or best bid (for a sell).

Trading hours

  • Borsa Italiana: 9:00-17:30 CET, Monday-Friday (except holidays).
  • Xetra: 9:00-17:30 CET.
  • LSE: 8:00-16:30 GMT.
  • NYSE / Nasdaq: 15:30-22:00 CET (US afternoon).

European ETFs don’t trade during US hours (or trade with thin liquidity). If you want to trade an S&P 500 ETF, the liquidity on European exchanges is best during European trading hours.

Primary vs secondary market

  • Primary market: when a company issues new shares (IPO) or bonds. You buy from the issuer.
  • Secondary market: ongoing trading of existing shares between investors. The exchange you see.

As retail, you mostly trade secondary. ETFs are a bit special — the “authorized participant” mechanism creates/redeems shares against the fund, keeping ETF price close to NAV. But you, the retail buyer, always trade on the secondary market.

Index changes

Indices aren’t static. Constituents are added or removed periodically:

  • Companies that grow big enough to qualify get added (inclusion effect — often a temporary price bump).
  • Companies that shrink or delist get removed.
  • Rebalancing typically quarterly.

When an index changes, index ETFs buy or sell to match. This creates predictable trading flows around rebalance dates. Occasionally exploitable by arbitrageurs, not usefully by retail.

Bond indices (briefly)

Similar concept for bonds:

  • Bloomberg Euro Aggregate — EUR-denominated investment-grade bonds.
  • iBoxx EUR Corporates — EUR corporate bonds.
  • ICE BofA Global Bond Aggregate — global fixed income.

Bond indices are harder to replicate because bonds are less liquid than stocks. Some bond ETFs use sampling rather than full replication.

The “best ETF” question

Sofia’s question from the top: “which S&P 500 ETF should I buy?”

Options available to Italian retail on Borsa Italiana:

  • iShares Core S&P 500 UCITS ETF (Acc) — IE00B5BMR087 — TER 0.07%.
  • Vanguard S&P 500 UCITS ETF (Acc) — IE00BFMXXD54 — TER 0.07%.
  • SPDR S&P 500 UCITS ETF (Acc) — IE00B6YX5C33 — TER 0.03%.
  • Xtrackers S&P 500 UCITS ETF (Acc) — IE00BM67HT60 — TER 0.07%.

All four track the same index. Differences: TER varies by 0.04 percentage points, replication method, AUM size, liquidity on specific listings.

Practical advice: any of these is fine. The differences between them pale next to the similarity. Pick one, don’t overthink.

What to do with this lesson

Three things:

  1. When buying an ETF, check its listing on Borsa Italiana in EUR first. Saves FX costs.
  2. Verify the ISIN, not just the name. “iShares MSCI World” has 4 different ISINs depending on share class and listing.
  3. Don’t spend weeks optimizing TER. Difference between 0.05% and 0.20% over 30 years on €10,000 is €450. Real, but not worth 30 hours of research.

Sources

  • MSCI — Index methodology. https://www.msci.com/our-solutions/indexes/index-methodology.
  • FTSE Russell — All-World index series. https://www.ftserussell.com/products/indices/all-world.
  • S&P Dow Jones Indices — S&P 500 methodology. https://www.spglobal.com/spdji/en/indices/equity/sp-500/.
  • Borsa Italiana — Trading rules and hours. https://www.borsaitaliana.it/.

Next lesson: price discovery, bid-ask, and slippage — why you pay slightly more than the quote, how to manage it, and the difference between market orders and limit orders.

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