Italian utility Enel (ENEI.MI) could raise 3.1 billion euros ($3.8 billion) with the flotation of up to 22 percent of its Spanish subsidiary Endesa (ELE.MC) on the stock market, according to the prospectus lodged with regulators on Thursday.

The listing is part of a plan by Enel, which owns 92 percent of Endesa, to increase its Spanish subsidiary's free float and reduce its own debt.

The maximum price for the retail placement has been set at 15.535 euros per share, valuing Endesa at 20.7 billion euros and representing a 6 percent premium to its closing share price on Thursday of 14.665 euros.

In a move to attract investors, Endesa said it pledges to pay shareholders 84.5 percent of earnings in dividends in 2015 and 80.6 percent in 2016.

The placement, including a public offering of shares to retail investors as well as Spanish and international institutional investors, includes an overallotment option under which the joint global coordinators may acquire between 23 million and 30 million Endesa shares.

Banco Santander (SAN.MC), BBVA (BBVA.MC), Credit Suisse (CSGN.VX), and JP Morgan (JPM.N) are joint global coordinators on the deal.

Bookbuilding for the offer will run between Nov. 13 and Nov. 20, when the final price will be fixed.

The shares are due to begin trading on Nov. 27.