The flagship index of the Spanish stock exchange, the IBEX 35 reflects the performance of the 35 most liquid and capitalised companies listed on the Bolsa de Madrid. It is a key indicator of financial market performance in Spain. Launched in 1992, the IBEX 35 belongs to the Bolsas y Mercados Españoles (BME) group and represents a variety of sectors, from banking and telecommunications to energy and construction. Companies in the IBEX 35 are selected according to their market capitalisation and liquidity. The composition of the index is reviewed twice a year to ensure that it accurately represents the Spanish economy. As the main index on the Spanish stock exchange, the IBEX 35 is a good barometer of the economic health of the country, and by extension, the eurozone. Derivatives such as futures and options are available on the IBEX 35, allowing investors to speculate on index price movements or hedge against market risks. The IBEX 35 is particularly sensitive to economic, political and geopolitical events. When the property bubble burst in 2008, the IBEX 35 experienced considerable turbulence due to its exposure to the country's construction sector and major banks. This market is regulated by the Comisión Nacional del Mercado de Valores (CNMV), which ensures transparency and investor protection.