Gas Natural has revealed that it has offered E21.3 per share for Endesa in a stock and cash deal with a total value of E22.55 billion ($28.31 billion). Some 65% of the buyout purse will be made up of Gas Natural stock with the remainder made up in cash.

The offer is a 14.8% premium on Endesa’s market closing price at the end of last week and is conditional on 75% of Endesa shares being tendered.

Endesa rival Iberdrola is also believed to be involved in the deal, possibly through the sell on of certain assets on completion, which would ease the Spanish regulator’s worries about possible anti-competitive issues.

According to Gas Natural, if the merger is successful, the new group would be the third largest utility on the planet, with 16 million customers in Europe and more than 30 million in the wider world. However, some industry onlookers have predicted that the offer will be rejected by Endesa and it is unclear whether the power utility would entertain any comeback.