Shares in German speciality chemicals and plastics maker Evonik rose in their stock market debut on Thursday following a series of private placings.

By 1050 GMT the shares were trading at €32.96, up 2.4% on the price of the placing on Wednesday, when shares amounting to a 2.5% stake in the company were sold via an accelerated bookbuilding process and valuing the group at €15.4 billion ($20 billion).

Unlike a normal share flotation Evonik's sale was managed as a so-called "cold listing", whereby the owners had already sold 12% of the shares to institutional investors in two private placings over the last two months, and then sold a further 2.5% on Wednesday.

The owners, the RAG foundation which is responsible for the liabilities of Germany's former coalmining industry, and private equity investor CVC, chose the unusual procedure after several previous attempts at an IPO failed.

However, Germany's second-biggest chemicals maker behind BASF, said it was now in the frame to be included in Germany's midcap index.

"If everything goes according to plan, we will be in the MDax in September," Evonik's chief executive Klaus Engel said after ringing the bell at the appearance of the first Evonik share price quote on the Frankfurt market's screens.

Evonik's 14.5% free-float of readily tradeable shares is worth roughly €2.2 billion, and companies with a free float market capitalisation of over €1 billion usually qualify for the MDax index, while a €5 billion value is needed for inclusion in the Dax index.

Evonik's free float may increase further as CVC has said in the past that it will eventually sell more shares. No lock-up period has been set.

"We expect to see more liquidity in the stock in the coming months," Engel said.

In the first hours of trading, Evonik's shares outperformed the Stoxx 600 Europe chemicals sector index which was up 0.1%.

However, weaker demand in important customer markets such as automotive, electronics and construction have dimmed European chemical makers' earnings prospects this year.

Diversified healthcare group Bayer's on Thursday lowered forecasts for its plastics and chemicals unit.

Investment banks Mainfirst and Deutsche Bank organised the listing.