The sudden crash of the bonds and shares of GetBack has taken investors, analysts and regulators by surprise, weighing on share prices of other listed firms.
The ratings agency Fitch cut its rating for GetBack's debt to 'restricted default' on Thursday.
"The downgrade reflects Fitch's view that the partial non-payment on bonds (...) constitutes an uncured payment default,"
the rating agency said.
Earlier this week, Poland's financial regulator KNF asked prosecutors to investigate GetBack, adding that nearly 200 institutions and over 9,000 retail investors held the firm's bonds.
The company's shares have lost nearly 90 percent of their value since October. GetBack debuted in the stock market in July last year, attracting investors with its aggressive growth strategy.
The firm bought up large portfolios of distressed debt at much higher prices than its competitors at a time of robust economic growth in Poland, coupled by record low unemployment and quickly rising wages.
Several respected brokerages had a 'buy' recommendation on GetBack shares until late last year.
The mBank DM brokerage, indirectly controlled by Germany's Commerzbank, had recommended buying GetBack shares in November last year, praising the company's "above average effectiveness" and setting a target price of 33.4 zlotys (7 pounds). The recommendation was suspended on Apr. 16.
The shares of GetBack have since plunged to 3.75 zlotys and trading was indefinitely suspended by the regulator last week.
In February this year, GetBack said that rating agency S&P Global changed the outlook on the firm's B rating to 'positive', citing the growth outlook. S&P has since cut the outlook to negative and suspended the rating altogether.
GetBack Chief Executive Konrad Kakolewski was dismissed earlier this month.
The troubles of GetBack, which is controlled by the private equity funds led by Abris Capital Partners, have dragged down shares of other listed firms, including investment fund Quercus TFI.
GetBack had been planning share issues worth up to 70 percent of existing capital and said last week the new board was aiming to restore investors' trust in the company.
(Reporting by Marcin Goettig; Editing by Alexandra Hudson)
By Marcin Goettig