By William Wilkes and Monica Houston-Waesch

FRANKFURT--Uniper SE, the conventional power and trading unit of E.ON SE (EOAN.XE), said Monday that its estimated first-half earnings jumped following the strong performance of its gas business.

The company's key performance figure, adjusted earnings before interest, taxes and amortization, was 1.5 billion euros ($1.69 billion), up from EUR1 billion a year ago. Adjusted EBIT rose to EUR1.1 billion from EUR500 million in the first half of 2015.

The company said changes to gas contracts from Russia and the strong performance of its global commodities business were behind the gains.

Uniper hasn't yet generated earnings as an independent company. ​The estimated figures are included in group results E.ON reported Aug. 10. ​

E.ON is set to spin off Uniper in a hybrid stock award and listing deal in mid September. It will give shareholders one Uniper share for every 10 E.ON shares held and list the company, shedding over 53% of it. E.ON plans to sell the remainder over the medium term.

Uniper Chief Executive Klaus Schäfer said improvements in the regulatory environment outside Germany and rising wholesale energy prices are encouraging signs for the business.

"So we enter the run-up to the listing with some momentum on the operational side," Mr. Schäfer said.

Last week, E.ON CEO Johannes Teyssen said the book value of Uniper was around EUR11 billion, but the market valuation is likely to be considerably lower.

In April Uniper said it would divest at least EUR2 billion in operations by the end of 2018 to pare debt and costs.

Companies sometimes choose spinoffs over initial public offerings to avoid IPO fees​. A spinoff can also let a company​ ​achieve ​independence and immediately ​​gain a ​substantial free-float​ level.

Uniper has appointed J.P. Morgan and Morgan Stanley for the listing. The price for Uniper shares will be determined on the first day of trading, and a minimum trading price won't be underwritten by the banks.

Uniper said earlier this year it will pay out around EUR200 million in dividends for 2016, and base future dividends on free cash flow.

-Write to William Wilkes at william.wilkes@wsj.com

(END) Dow Jones Newswires

August 22, 2016 02:35 ET (06:35 GMT)