The port city bourse on Wednesday sent letters to its brokerage firms informing them of the revised trading period.
Presently, both the bourses conduct trading between 10am and 2.30pm.
The port city bourse said it would start trading at 9.30am, instead of 10:00am, and close at 2:45pm, instead of 2:30pm.
In a press release, the DSE Brokers Association (DBA) said separate trading period for two bourses in the same country and same time zone is 'unprecedented'.
DBA President Saiful Islam said the extended trading period would create scope of stock price manipulation. So, the CSE should withdraw its decision.
CSE Managing Director M Shaifur Rahman Mazumder said DBA was worried because of misunderstanding.
The trading period has been extended in line with the existing rules in a bid to offer a diversification in trading, he said.
Mohammad Rezaul Karim, a BSEC spokesperson, said an exchange has the authority to decide trading period in compliance with regulations.
"The securities regulator has nothing to do here," he added.
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