According to a Coface study released on Wednesday, 1,770 Romanian firms in the retail industry, 1,501 in wholesale trade and another 822 companies in the construction sector were insolvent by the end of the first half of 2008.
Lack of liquidity is the main problem for companies unable to pay their debts, the agency said.
"Expansion of large international super- and hypermarket chains has led to an increase in the number of smaller businesses going bust in this sector," Coface said.
The construction industry remains the riskiest business, according to the survey.
Other industries with high levels of possible bankruptcy include transportation, food and hotel/restaurant services.
Of the 618,000 companies registered in Romania at the end of 2007, 311,573 reported profit while the remaining 306,424 finished the year in the red, Coface said. Those with outstanding debts to the state numbered 92,952.