Two sources with knowledge of the situation said on Tuesday that Abu Dhabi National Oil Company (ADNOC) has approached German plastics and chemicals manufacturer Covestro AG (1COV.DE) with a buyout proposal for more than 10 billion euros ($10.9 billion).

The sources, who asked not to be identified because the subject is private, claimed that the energy giant has made an informal offer for a per-share price in the mid-50 euro range, which compared to a Monday closing price of 40.31 euro.

Covestro, a maker of transparent polycarbonate plastics, as well as chemicals for insulation and upholstery foams, in April issued earnings guidance that reassured markets about its growth prospects. It also resumed a share buyback programme.

Earlier on Tuesday it confirmed its outlook for 2023.

Shares in Covestro were up 14% at 46 euros at 1400 GMT, trading at their highest in more than a year.

A combination would give energy giant ADNOC, also a maker of refined products and petrochemicals, access to more advanced materials that go into electric vehicles, thermal insulation for buildings as well as coatings, adhesives and engineering plastics.

It would also support Abu Dhabi’s plans to diversify the economy away from energy.

As part of that transformation strategy, which also invited foreign investment, ADNOC began floating units in late 2017.

Over the past two years, it has separately listed businesses offering investors exposure to its petrochemicals, fertilisers, drilling services, gas as well as logistics businesses.

ADNOC Chief Executive Sultan al-Jaber is leading the company’s push into new energy, low carbon fuels, such as ammonia and hydrogen, as well as liquefied natural gas and chemicals.

ADNOC has expanded in Europe previously, agreeing to buy 24.9% of Austrian oil and gas group OMV (OMVV.VI) last December.

The OMV deal would indirectly also increase ADNOC’s holding in both European petrochemicals maker Borealis and Abu Dhabi-listed petrochemicals company Borouge (BOROUGE.AD).

A move for Covestro would mirror the expansion of other Middle Eastern energy and petrochemical players into European materials and plastics businesses.

Saudi Aramco in 2018 acquired the shares it did not already own in synthetic-rubber maker Arlanxeo from German co-owner Lanxess (LXSG.DE) for 1.4 billion euros.

SABIC (2020.SE), also of Saudi Arabia, in the same year purchased a stake of almost 25% in Swiss chemicals maker Clariant (CLN.S).

Thanks to a 2007 deal to buy GE’s plastics unit, SABIC competes with Covestro in polycarbonate plastics.