A retired stockbroker from Malaysia who lost US$26 million (S$35.3 million) in investments with Credit Suisse during the 2008 financial crisis is suing the Singapore branch of the Swiss bank for breaching its duties to manage his private wealth account with care.

Mr Koh Kim Teck, 63, alleges that the bank had wrongly advised him to invest in high-risk structured products that were unsuitable for his objectives of wealth preservation.

He claims that the bank had failed to monitor and keep him informed of the risk exposure of the account, which was opened in the name of his offshore corporate vehicle.

He also alleges that it was unreasonable for the bank to give him only four hours' notice to top up an additional US$5.7 million in collateral before closing out his account, which resulted in the losses.

On Tuesday, the first day of a three-week trial, his lawyers, Senior Counsel Sarjit Singh Gill and Mr Edmund Eng, portrayed him as a man of substantial wealth who was relentlessly courted by bank employees pushing high-risk products.

"In its single-minded pursuit of extraordinary profits, the defendant simply closed its eyes to the duties it owed to the plaintiff," said Mr Koh's lawyers in their opening statement.

The lawyers said Credit Suisse had promised Mr Koh "the heavens and the stars" when trying to get him to open a private wealth account with the bank. But "when the music stopped", the bank closed out his account after a "farcical" four hours' notice, wiping out his nest egg.

Credit Suisse, represented by Senior Counsel Alvin Yeo and Ms Lim Wei Lee, contended that the losses were a consequence of Mr Koh's own investment decisions and the global financial crisis, not through any fault of the bank.

The bank disputed Mr Koh's attempt to portray himself as having been led astray by its employees. It said Mr Koh, who retired as the general manager of a prominent stockbroking company listed in Malaysia, was a sophisticated and savvy investor.

Credit Suisse contends that Mr Koh was actively managing the investments in the account, apart from a period between 2004 and 2005 when he was busy defending a criminal charge of murdering his teenage nephew in Malaysia. Mr Koh was eventually acquitted at trial.

Both sides have diametrically opposite accounts of what led to the opening of the account in 2003.

Mr Koh's version is that a bank employee pursued him to open the account and he relented after she promised that the bank would set up an offshore company through which he could hold the account.

She also assured him that the bank would monitor the account and advise him on his investments, said Mr Koh.

He alleged that in 2007, the bank unilaterally increased his risk tolerance to "high" and introduced riskier investments to him in the form of structured products known as accumulators, which have been dubbed "I kill you later".

However, Credit Suisse contended that it was Mr Koh who wanted to open an account with the bank using using an offshore vehicle for confidentiality. He had also expressed interest in high-yield investment products to enhance his returns, said the bank.

The bank said Mr Koh did not object to the close-out of his account and had instead thanked the team for their hard work. Five years later, in 2013, he sued the bank. His investment vehicle, Smiling Sun Limited, also filed suit against the bank.