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What is the IBEX 35 Index?
What is the IBEX 35 Index?

What is the IBEX 35 Index?

The IBEX 35 is the leading benchmark index for the stock market in Spain. The index includes 35 of the largest and most liquid stocks listed on the Madrid Stock Exchange. The index is heavily weighted to financial services, communications, and utilities companies. It is considered a gauge for the Spanish stock market and economy.

The Index is also known as the Spain 35 index.

IBEX 35 definition

The IBEX 35 (Índice Bursátil Españo Index) is a free float market capitalization weighted index of the most liquid stocks listed on the Madrid Stock Exchange. The index is rebalanced twice each year to ensure that the 35 most liquid stocks on the exchange remain in the index.

History of the IBEX 35

The IBEX35 index was launched in 1992 and recorded its lowest ever level later the same year. The index then strengthened through the rest of the 1990s, trading as high as 12968 in early 2000. Like many indexes the IBEX declined substantially in 2001 and 2002 after the Dotcom bubble burst.

The index had its strongest rally from 2003 to 2007, when the construction and real estate sectors were booming. This was followed by a period of record volatility while the Global Financial Crisis played out between 2007 and 2009. A recovery was short lived, as the European Debt Crisis followed in 2011, with Spain amongst the worst affected countries. 

Since then, the IBEX35 has lagged other country indexes due to its low exposure to technology and growth stocks. The index has remained in a sideways trading range between 6000 and 12000 since 2009.

How the IBEX 35 in calculated 

The IBEX 35 is based on free float market capitalizations, which are not capped. A company’s free float is the number of outstanding shares that are not restricted or held by related parties. The free float is expressed as a percentage which is multiplied by the market capitalization to arrive at the free float market capitalization.

To calculate the weight of each company, the sum of the free float market capitalizations of all 35 companies is first calculated. The weighting of each company is then calculated by dividing its free float market capitalization by the total value of all 35 companies.

To calculate the index level, the total free float market cap of all 35 companies is divided by the same value for a base period, and then multiplied by the index level for that base period.

Some market capitalization weighted indexes have a cap on the weight of each company - however, this is not the case for the IBEX index.

close view stock market data board

How Does IBEX 35 Work?

The IBEX 35 index is maintained by Bolsas y Mercados Españoles, which also manages financial markets in Spain. The index is reviewed by a technical advisory committee twice each year, in June and December.

Any changes to the index are based on the six-month period prior to the review. The primary criteria for inclusion is liquidity, rather than market value. 

The stocks that are included are the 35 companies with the highest traded value over the review period, provided that they account for at least 0.3% of the total index value and trade on more than 33% of trading days, or fall into the 20 most valuable companies. 

Any changes that are made come into effect on the first trading day following the third Friday of the review month.

IBEX 35 Companies

The following are the largest 10 companies in the index and account for 71% of the total weight of the index.






Iberdrola SA





Industria De Diseno Textil SA


Consumer Cyclical

Apparel Retail


Banco Santander SA


Financial Services



Cellnex Telecom SA


Communication Services

Telecom Services


Amadeus IT Group SA A



IT Services


Telefonica SA


Communication Services

Telecom Services


Ferrovial SA





Banco Bilbao Vizcaya Argentaria SA


Financial Services






Airports and Air Services


CaixaBank SA


Financial Services



Prominent companies

The following three companies account for nearly a third of the market capitalization of the index.

Iberdrola SA

Iberdrola is a power utility that generates and distributes electricity in Spain, UK, USA and Brazil. The company employs 34,000 people and has a market value of €69 billion, making it the second most valuable company in Spain

bilbao spain

Industria De Diseno Textil SA

ITX is an apparel and household product retailer. The company’s brands include Zara, Pull & Bear, Massimo Dutti, Bershka, Stradivarius, Oysho and Zara Home.

With a market value of €75 billion, ITX is the most valuable company in Spain, however it’s low free float reduces its weight in the index. 

Banco Santander SA

Banco Santander is the largest financial services group in Spain. The company also operates globally and has a total of 11,950 branches. The company has a market value of €27 billion.


The IBEX 35 index has not performed well over the last decade. However, it is relatively volatile and often trades in a clearly defined range. These characteristics make it ideal for trading with instruments like CFDs. 

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