Five big enterprises saw their “certification of excellence in fair trade” withdrawn after being named to have engaged in irregular practices including price fixing.

The Fair Trade Commission said Sunday that it has downgraded the fair trade assessments on POSCO, POSCO C&C, Samsung Construction & Trade Corp., Hyundai Mobis and Shinsegae.

While 27 companies were granted the certification from the antitrust regulator at the end of last year, the five players have been excluded from the fair trader list due to the ratings downgrade.

The rating of POSCO fell by two notches from “AA” to “BBB” as the company was implicated in a cartel for steel product prices. The FTC levied 98.3 billion won ($86.9 million) in fines on POSCO and filed a complaint against the steel producer with the prosecution.

POSCO C&C, which underwent a drop from “A” to “BB,” has also been placed under criminal investigation, being slapped with antitrust fines.

The two affiliated firms and five other competitors are said to have been involved in separate price-collusion cases between 2004 and 2010.

Samsung C&T Corp. and more than 10 builders were suspected of engaging in cartel activities during their participation in former President Lee Myung-bak’s project to refurbish the country’s four major rivers.

The builders allegedly manipulated construction costs totaling about 1 trillion won and sharing districts via back-room deals.

Samsung C&T Corp., which was fined 10.3 billion won, saw its rating fall to “BBB” from earlier “A.”

The FTC also lowered its assessment on Hyundai Mobis from “A” to “BBB” for bullying subcontractors.

Shinsegae has also been disqualified from the fair trader list as the regulator revealed the company’s irregular funding to subsidiaries or sister firms.

The FTC had not deprived companies of the accreditation on the list despite some of their irregular practices.

Due to the regulator’s policy-shift, more companies are likely to be blocked from the “pardon.”

By Kim Yon-se (kys@heraldcorp.com)