The short answer: MSCI World covers developed markets only. FTSE All-World and MSCI ACWI add emerging markets. None of the three includes the full small-cap segment, so “world” and “all-world” still do not mean every listed company.
The decision that matters most is whether emerging markets belong inside this holding. MSCI World leaves that allocation to the investor. FTSE All-World and MSCI ACWI include it at market weight and are closer substitutes for one another. After that coverage decision, the available ETF’s charge, tracking, replication, domicile and trading costs can matter more than the provider name.
Coverage compared
| Index | Developed markets | Emerging markets | Company sizes | Provider coverage target |
|---|---|---|---|---|
| MSCI World | Yes | No | Large and mid cap | About 85% of free-float market capitalisation in each developed country |
| FTSE All-World | Yes | Yes | Large and mid cap | Targets 90% coverage of the nine regional universes used in FTSE GEIS |
| MSCI ACWI | Yes | Yes | Large and mid cap | About 85% of the global investable equity opportunity set |
Those percentages use each provider’s own construction system, so 90% versus 85% is not a clean scorecard. FTSE applies regional size bands; MSCI describes coverage within its free-float-adjusted country universes. Constituent counts also change at reviews and with corporate actions. They are useful snapshots, not permanent product specifications.
The largest difference is emerging markets
MSCI World includes developed markets such as the United States, Japan, the United Kingdom and Canada. It excludes markets MSCI classifies as emerging. An investor who uses MSCI World and wants those markets must add a separate emerging-markets holding and choose its weight.
FTSE All-World and MSCI ACWI incorporate developed and emerging markets in one index. Their emerging-market weights move with free-float-adjusted market values. They can still disagree about individual country classifications. That difference can place a market in the developed segment under one provider and the emerging segment under another without making either index universally “correct”.
Do not mix index providers blindly
Country classifications can differ between MSCI and FTSE. In a one-fund all-country portfolio, the index provider handles those boundaries internally. In a two-fund portfolio, combining a developed-markets index from one provider with an emerging-markets index from another can omit or double-count a market. Use one index family for both sleeves or inspect the overlap explicitly.
None of the three solves small-cap exposure
All three indexes stop at large and mid caps. Investors who intentionally want smaller listed companies need an all-cap or investable-market index, or a separate small-cap holding. MSCI ACWI IMI, for example, extends the MSCI universe into small caps. FTSE Global All Cap does the same within the FTSE system.
More securities do not automatically mean a better outcome. Small-cap coverage changes diversification, implementation cost and tracking. The useful question is whether the extra segment belongs in the intended portfolio, not which index has the largest constituent count on one date.
Why similar global indexes can produce different returns
Provider rules affect country assignment, free-float adjustments, size cut-offs, buffers, review dates and the treatment of corporate events. Those choices change holdings and weights. The indexes will often move similarly because they share many of the world’s largest companies, but their returns will not be identical.
Currency also needs careful language. An ETF’s trading currency is the currency used to buy a listing; it does not remove the underlying companies’ currency exposures. A USD share class bought in euros can still hold businesses earning revenue across many currencies. A currency-hedged share class is a separate design decision.
A decision framework
- Choose the intended market set first. Decide whether emerging markets should be inside this holding.
- Check company-size coverage. Add small caps only when the extra exposure is intentional.
- Compare investable funds, not index names alone. Charges, tracking difference, replication, domicile, tax treatment, spread and platform availability can outweigh a small methodology difference.
- Avoid performance chasing. A recent winner may simply have held more of the countries, sectors or companies that led during that period.
For a developed-markets-only allocation, MSCI World states the boundary clearly. For a single large- and mid-cap global holding that includes emerging markets, FTSE All-World and MSCI ACWI are closer comparisons. The choice between them should be made through the available fund implementation, not by assuming one brand is inherently superior.
Frequently asked questions
Does MSCI World include emerging markets?
No. MSCI World is a developed-markets index. An investor who wants emerging markets must add a separate allocation or use an all-country index such as MSCI ACWI or FTSE All-World.
Is FTSE All-World broader than MSCI ACWI?
Both cover developed and emerging large- and mid-cap equities. Their constituent counts and country rules differ, but a higher count is not automatically a better portfolio. Compare the investable funds and the weight of the extra holdings.
Do any of these indexes include small caps?
Not as a complete small-cap segment. MSCI ACWI IMI and FTSE Global All Cap are examples of broader families that extend into small companies.
Sources and limitations
MSCI describes MSCI World as large- and mid-cap exposure across developed markets, covering about 85% of free-float-adjusted market capitalisation in each country. MSCI’s ACWI factsheet describes developed and emerging large- and mid-cap coverage and approximately 85% of the global investable equity opportunity set. FTSE Russell’s All-World overview documents its large- and mid-cap scope, developed/emerging coverage and regional construction process.
This comparison concerns index design. It does not rank providers, recommend a fund or model tax. Index membership, country classification and constituent counts can change; recheck current provider documents before acting.