A Yugoslav war refugee turned Swedish property tycoon is fast running out of options to stabilize his $13 billion empire, and the outcome will have ripple effects across Europe’s real estate industry.

Ilija Batljan started amassing a portfolio of more than 2,000 properties in 2016, buying up social housing and municipal buildings from cash-strapped authorities and leasing them back. The idea was to combine steady growth with stable returns provided by reliable, long-term tenants — but the reality was an appetite for debt that was too much for the Swedish market.