The nation’s antitrust watchdog launched on Tuesday an investigation into the possible collusion among local brokerages on their certificate of deposit rates, the benchmark for borrowing costs of local banks.

According to industry sources, the Fair Trade Commission dispatched investigators earlier in the day to the nation’s 10 brokerages to secure relevant computer data and documents.

The securities firms included Leading Investment & Securities, Dongbu Securities, Meritz Securities, Mirae Asset Securities, Woori Investment & Securities, Hana Daetoo Securities, Hanwha Securities, KB Investment & Securities, KTB Securities and LIG Investment & Securities.

The CD rates here are announced twice, at 11:30 a.m. and 3:30 p.m., every day after the Korea Financial Investment Association calculates the average of figures collected from the nation’s top brokerages.

The decision-making process, however, has caused a transparency debate recently as the CD rates remain high despite the fall of market rates.

The FTC declined to confirm the details of the ongoing investigation, citing the agency’s policy.

By Lee Ji-yoon (jylee@heraldcorp.com)