UK and FTSE Indexes

UK and FTSE indexes measure defined segments of the UK equity market under published eligibility, weighting, calculation, and maintenance rules. This section distinguishes the FTSE Russell provider and index family from the FTSE 100, the broad FTSE All-Share, and the historical FT 30.

Start With the Right Term

Index Relationships

The FTSE 100 and FTSE 250 are complementary large- and mid-cap segments. Together they form the FTSE 350. Adding FTSE SmallCap coverage produces the FTSE All-Share universe under the current FTSE UK Index Series framework.

These are membership relationships, not arithmetic relationships between published index levels. Each index has its own divisor and base, so their point levels cannot be added or compared as amounts.

What to Verify

Before using a UK index statistic, check:

• complete index name, ticker, provider, and data vendor;
• eligible market and security types;
• full-market-cap ranking versus free-float-adjusted weighting;
• constituent and weight effective date;
• scheduled review and corporate-action treatment;
• price, gross total return, or net total return;
• reporting currency and any currency hedge;
• concentration by company, sector, and revenue geography; and
• whether the cited return belongs to the index or an investable product.

Common Mistakes

• Using FTSE as though it always means FTSE 100.
• Calling FTSE a stock exchange rather than an index brand and provider.
• Assuming a UK index measures only revenue earned in the UK.
• Treating broad coverage as equal weighting or absence of concentration.
• Comparing price return with total return or mixing currencies and dates.
• Assuming index membership is a recommendation, credit opinion, or liquidity guarantee.
• Applying current constituents or methodology to an older historical series.

Indexes are measurement and benchmarking tools. Funds, derivatives, and other products linked to them carry separate fees, tax treatment, liquidity, tracking, leverage, and counterparty risks. This section provides education, not personalized investment advice.

In this section

Choose a subsection first. Deeper term pages live inside each subsection, which keeps large topic hubs readable.