An investment fund that hid flaws in a computer trading application has agreed to pay a $25 million SEC fine and refund $217 million in losses suffered by investors because of the problem.

AXA Rosenburg Group caught a coding error last April, but the employees who found it tried to keep others from finding out and failed to report it to higher-ups, the company says, according to a story in the Wall Street Journal.

When investors complained that their portfolios were performing badly, the company told them market volatility among other things but not including the software flaw, were to blame, the Securities and Exchange Commission says, according to the Wall Street Journal. The company had been charged with fraud.

AXA is a quantitative investment fund, which is a category of fund that uses computer models to decide trading strategies, and the SEC looking harder at them and their algorithms because of the potential to increase risk to investors and also to disrupt markets, the report says.

Of concern is whether these funds tell investors enough about the risks involved in the way they determine what to invest in and whether these quantitative funds act together to manipulate prices, the report says.