Kesara Manchusree, president of the SET, said on Saturday that the Thai capital market was protected from any shock that might happen as a result of the verdict.
Yingluck is accused of being negligent in her duty to supervise an allegedly corrupt rice-pledging scheme. The Supreme Court will hand down its verdict on August 25.
Kesara said the stock market had been through many political upheaval events in the past. Investors were now more mature, and the stock market had tools to deal with the issue, she said on Saturday.
Foreign investors viewed the Thai capital market as attractive for long-term investment, so any event, rumours or speculation, would have only a short-term impact on the market, she said.