(Bloomberg) -- A former Deutsche Boerse AG employee confessed he secretly traded for three and a half years on non-public information the Frankfurt stock exchange received from listed companies.

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The man, who can only be identified as G. P., is being tried in Germany over 14 counts of insider trading between January 2018 and July 2021. On the first day of trial he admitted to using information Deutsche Boerse received 30 minutes before the filings were made public. He traded stocks in companies including Deutsche Bank AG and Aurubis AG.

“I didn’t feel comfortable when I did this,” G. P. told the Frankfurt judges on Monday. “I did something stupid. I still have sleepless nights.”

The ex-Deutsche Boerse staffer was investigated over 154 cases of insider trading and prosecutors have provisionally seized €1.3 million ($1.4 million) of his assets.

Because it wasn’t clear in most of the filings whether they contained actual insider information, the prosecution was narrowed to 14 counts. The court is likely to seize only €163,000 and hand him a suspended sentence, given the accused has cooperated with authorities, Presiding Judge Eva-Marie Distler said.

The 53-year-old worked at Deutsche Boerse’s cash market operation unit, which monitored the filings to decide whether it was necessary to suspend trading in a company.

G. P., who’d been at Deutsche Boerse since 2006, at the time sat in a room with about 30 co-workers. Still, he used his company desktop to place the trades. He usually bought or sold stock within the 30 minutes and then unwound the trade shortly after the information went public. Nobody at Deutsche Boerse ever noticed anything or controlled what he was doing there, he told the court.

Deutsche Boerse has cooperated fully with the authorities, the company said in a statement, calling the affair an isolated case.

It also took German financial regulator Bafin four years to track his actions. A Bafin employee testified on Monday that his deals were simply too small and went unnoticed.

He sold the securities in his first trade for €1,400 while later transactions brought in up to several thousand euros. All 14 trades added to a turnover of €163,000. He invested €27,000 and his profits were €70,000, according to his lawyer Felix Rettenmaier.

G. P. also traded in Wirecard in 2020 ahead of the company disclosing that €1.9 billion was missing from its accounts. He bought put options, betting on falling shares. When the information was released to the markets, the stock plunged 62%.