Shares of Poland-based ecommerce platform Allegro soared more than 50% on their debut on the Warsaw stock exchange on Monday to give the firm a stock market value of about $17.6 billion in Europe’s biggest IPO so far this year.

Allegro immediately became the most valued company on the Warsaw exchange.

Allegro said the offering comprised the issuance of 23,255,814 new sale shares and and the sale of 190,293,225 existing sale shares by existing shareholders.

The free float will be 20.9%, before any exercise of the over-allotment option.

Allegro CEO François Nuyts said: “With our IPO process now complete, we can now look forward to starting Allegro’s next phase of growth as a listed company …

“The engagement we have seen from institutional and retail investors over recent weeks has been humbling.

“I’d like to thank each of them for their interaction with us and welcome those who have decided to become shareholders in Allegro.

“I am particularly delighted that today Allegro employees also become shareholders in the company, enabling them to share in the future success we go on to create together.”

Goldman Sachs, Morgan Stanley, Barclays, Bank of America, Citigroup, Santander and BM PKO BP helped arrange the Allegro IPO.