The Spanish stock market regulator said Friday more than 487.6 million shares had been tendered. Acciona and Enel were already the top shareholders in Endesa, with a combined 46 percent stake.

The successful tender marks the end of a two-year saga which began in September 2005, when Spanish gas distributor Gas Natural launched a hostile cash-and-shares offer for Endesa, later responded to by counterbids from Germany's E.ON AG.

Acciona and Enel trumped E.ON's bid by acquiring stakes in Endesa, then in April the two companies formally launched a joint takeover bid for Endesa at euro41.30 a share. The offer was later lowered to euro40.16 a share to adjust for an euro1.14-a-share dividend paid by Endesa on July 2. The bid valued Endesa at euro42.53 billion ($60.01 billion).

The bidding battle caused a political headache for Spain's government, which initially supported Gas Natural's offer, sparking a conflict with the European Commission.

Earlier this year, E.ON agreed to step back from the bidding battle in exchange for a plan to purchase about euro10 billion worth of assets in Spain, Italy, France and Turkey currently in the hands of both bidders and Endesa.

Under the terms of Enel and Acciona's agreement, Endesa will remain a Spanish firm, controlled by a joint holding company in which Acciona will have a 50.01 percent majority. Acciona will appoint the executive chairman of Endesa, and Enel will appoint the chief executive.

Endesa's renewable energy assets will be merged with Acciona's energy division to create a separate renewable energy company in which Acciona will have at least a 51 percent stake and Endesa the remainder.

The Endesa takeover deal also stipulates a potential asset split between Acciona and Enel, if they encounter irreconcilable differences while managing the company.

Endesa shares were down 0.64 percent at euro38.52 ($54.35).