Selection

The composition of the IBEX 35 is reviewed twice per year (in June and December)^[12] by the so-called Technical Advisory Committee, which consists of "representatives of the stock exchanges and derivatives markets, as well as... renowned experts from the academic and financial fields".^[12] If any changes are made, they come into effect the following trading day after the third Friday of the rebalance month^[13][12] In general, at each review, the 35 companies with the highest trading volume in Euros over the previous six months are chosen for inclusion in the index, provided that the average free float market capitalization of the stock is at least 0.3% of the total market cap of the index.^[5] Any candidate stock must also have either been traded on at least a third of all trading days in the previous six months,^[12] or rank in the top twenty overall in market cap^[14] (thus allowing large recently IPOed companies to be included).

Weighting

The IBEX 35 is a capitalization-weighted index.^[12] The market cap used to calculate the weighting of each constituent is multiplied by a free float factor (ranging from 0.1 to 1) depending on the fraction of shares not subject to block ownership.^[5] Any company with 50% or more of its shares considered free float is given a free float factor of 1.^[5] Unlike many other European benchmark indices, the weightings of companies in the IBEX 35 are not capped.

As of 2015, international funds based abroad (chiefly in Norway, the United States, the United Kingdom and Qatar) owned 43% of the index, vs. 16% in 1992.^[15] Such rate of foreign investment was about 5% above the EU average.^[15]

Calculation

The index value (given here as I) of the IBEX 35 index is calculated using the following formula:^[5]

${\displaystyle I(t)=I(t-1)\times {\frac {\sum _{i=1}^{35}{\rm {Cap}}_{i}(t)\,}{[\,\sum _{i=1}^{35}{\rm {Cap}}_{i}(t-1)\,\pm J\,]\,}}}$

with t the moment of calculation; Cap the free float market cap of a specific listing and J a coefficient used to adjust the index on the back of capital increases or other corporate actions so as to ensure continuity. The formula can be adjusted to accommodate changes in index structure, such as the temporary suspension of companies pending news.

Specification

IBEX Mini futures contracts are traded on the MEFF Renta Variable (MEFF-RV) exchange under the ticker symbol BIBX. The full contract specifiactions for IBEX Mini futures are listed below.