Through its subsidiary Enel Energy Europe, Enel has finalized a share swap transaction with UBS Limited, whose underlying security is represented by a maximum of 74,112,648 shares of Endesa (equal to 7% of the latter’s share capital).

The move comes just a day after Enel completed the acquisition of 105,800,000 shares of Endesa, representing 9.99% of the company’s share capital. The purchase price was E39 per share, for a total consideration of E4.1 billion.

The developments will be of increasing concern to E.ON. The German power firm has been pursuing the total acquisition of Endesa for some time and had looked clear to achieve its goal after seeing off a rival bid from Gas Natural and legal issues. However, Enel’s accumulation of shares has thrown fresh doubt on the takeover.