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Analysis-From war bunker to penthouse to market flop: how Germany's property boom ended

By Tom Sims and John O'Donnell

MUNICH (Reuters) - It has been a tumultuous year for one prominent German property developer: his efforts to sell his penthouse atop a Nazi-era air raid shelter have stalled, and just weeks ago his firm filed for insolvency.

The one-two punch for the developer, Stefan Hoeglmaier, and his company, Euroboden, mirror the travails of the broader property sector across Europe's largest economy as it suffers its worst slump in decades.

For years, low interest rates fuelled a global boom, igniting interest in German property, seen as safe and stable as the country.

A sharp rise in rates, and soaring energy and building costs, put an end to the run. That has tipped a string of developers into insolvency, frozen deals and pushed prices down, prompting the industry to appeal to Chancellor Olaf Scholz for help.

"We're heading for the wall at breakneck speed. The first developers have fallen and more will follow," said Tillmann Peeters, an insolvency lawyer with FalkenSteg.

Developers' fortunes, including Euroboden, changed in 2022 when the European Central Bank began to increase rates, making it harder for to borrow and to find buyers for projects.

A statement from Euroboden management said the market environment for the company had "deteriorated quite considerably".

The health of Germany's property sector - Europe's biggest property investment market outside of Britain - is critical, making up roughly a fifth of output and providing one in 10 jobs. New building during the first half of the year nearly halved from the past two years.

In 2010, in the early days of a years-long boom, Hoeglmaier bought a dilapidated aboveground bunker in a posh Munich neighbourhood from the government to convert it into luxury apartments.

He and his partner Oscar Loya – a Eurovision Song Contest star – took for themselves the three-floor penthouse, complete with music room and gold-leaf walls in the toilet.

During the decade that followed, Euroboden completed projects with renowned architects, generated tens of millions of euros in profit, raised millions from investors, and expanded to Berlin and beyond.

The penthouse made the cover of Germany's Architectural Digest, and the couple hosted "bunker acoustic sessions", with video clips posted to Loya's Facebook page.

Loya, who owns stakes in two Euroboden subsidiaries, also serenaded staff at the company's 20-year anniversary party in 2019.

The property boom came to an abrupt end last year when the speed of interest rate increases caught many in the sector off guard.