FTSE 350

FTSE 350 is a stock market index that represents the combined performance of the constituents of the FTSE 100 and FTSE 250 indices. It therefore comprises 350 large- and mid-capitalisation companies that meet the applicable size, liquidity, and other eligibility requirements of the FTSE UK Index Series. The index is calculated and maintained by FTSE Russell.

The FTSE 350 provides broader exposure to the large- and mid-cap segments of the UK equity market than either the FTSE 100 or FTSE 250 individually.

Composition

The FTSE 350 consists of:

the 100 constituents of the FTSE 100;
the 250 constituents of the FTSE 250.

A simplified relationship is:

$FTSE 350 = FTSE 100 + FTSE 250$

FTSE Russell describes the FTSE 350 as an aggregate index representing large- and mid-cap stocks traded on the London Stock Exchange.

Market capitalization

The FTSE 350 covers companies across the large- and mid-capitalisation segments of the UK equity market.

A simplified calculation of market capitalization is:

$Market Capitalization = Share Price \times Shares Outstanding$

For index purposes, FTSE Russell applies free-float and other methodology adjustments to determine the investable market capitalization of constituents.

Index weighting

The FTSE 350 uses a market-capitalisation-weighted methodology based on free-float-adjusted market values.

A simplified representation of a constituent's index weight is:

$Index Weight = \frac{Free-Float-Adjusted Market Capitalization of Constituent}{Total Free-Float-Adjusted Market Capitalization of Index} \times 100 %$

The actual index calculation incorporates the FTSE UK Index Series methodology and its applicable rules.

Free float

Free float refers broadly to the proportion of a company's shares considered available to public investors.

FTSE Russell uses free-float adjustments when determining the market value used for index weighting. This means that the index weight of a company does not necessarily correspond directly to its total market capitalization.

FTSE 100 and FTSE 250

The FTSE 100 represents the largest 100 eligible companies in the FTSE UK Index Series, while the FTSE 250 represents the next 250 largest eligible companies.

The FTSE 350 combines both segments.

The FTSE 350 therefore provides broader representation of large- and medium-sized UK-listed companies than the FTSE 100 alone.

The FTSE All-Share Index is broader than the FTSE 350.

It combines:

FTSE 100;
FTSE 250;
FTSE SmallCap.

A simplified relationship is:

$FTSE All-Share = FTSE 100 + FTSE 250 + FTSE SmallCap$

The FTSE All-Share represents approximately 98–99% of UK market capitalisation according to FTSE Russell.

FTSE SmallCap

The FTSE SmallCap represents eligible companies that are not large enough to be included in the FTSE 350.

The broad structure can therefore be represented as:

$FTSE All-Share = FTSE 350 + FTSE SmallCap$

subject to the applicable FTSE UK Index Series rules.

Index reviews

The FTSE 350 is maintained through the review process of the FTSE UK Index Series.

FTSE Russell conducts periodic reviews to ensure that the indices continue to represent their intended market segments. Corporate actions and other changes can also result in constituent changes between scheduled reviews. :contentReference[oaicite:6]{index=6}

Companies can move between the FTSE 100 and FTSE 250 as their relative market capitalizations change.

For example, at the June 2026 annual review, Berkeley Group Holdings, Mondi, and Rightmove moved from the FTSE 100 to the FTSE 250, while other companies moved in the opposite direction.

Industry coverage

The FTSE 350 contains companies from multiple industries and sectors.

FTSE Russell also maintains FTSE 350 sector and supersector indices derived from the constituents of the FTSE 100 and FTSE 250.

Index calculation

A simplified price-index calculation is:

$Index Value = \frac{\sum_{i = 1}^{n} {Free-Float-Adjusted Market Value}_{i}}{Index Divisor}$

The divisor is adjusted for events such as corporate actions and constituent changes so that such events do not create artificial movements in the index.

Price and total-return indices

The FTSE UK Index Series supports different index variants, including price and total-return indices.

A price index measures changes in constituent prices.

A total-return index additionally incorporates dividends according to the applicable methodology.

A simplified representation is:

$Total Return = Capital Return + Dividend Return$

The precise calculation depends on the specific index variant.

Investment products

The FTSE 350 can serve as a benchmark or underlying index for financial products and investment strategies.

These may include:

index funds;
exchange-traded funds (ETFs);
structured products;
derivatives;
other index-linked investment products.

Investors can use such products to obtain diversified exposure to a broad group of large- and mid-cap UK companies.

Benchmark

The FTSE 350 can be used as a benchmark for portfolios investing in large- and mid-cap UK equities.

A fund manager can compare the performance of a portfolio with the FTSE 350 to assess relative performance.

A simplified active-return calculation is:

$Active Return = Portfolio Return - Benchmark Return$

Importance

The FTSE 350 is an important benchmark for the large- and mid-cap segments of the UK equity market. By combining the FTSE 100 and FTSE 250, it provides broader coverage than either index individually while remaining narrower than the FTSE All-Share. It is used for investment benchmarking, portfolio management, market analysis, and index-linked financial products.