ING says that it has fixed a problem with its systems that saw Dutch customers given incorrect balance information online and through their mobiles.
In a statement, the bank says that a problem with payment processing on Tuesday night, and the subsequent delay, meant that some transactions were temporarily duplicated.
The error pushed many customers incorrectly into the red and saw the bank inundated with angry messages on social networks such as Twitter.
Meanwhile, rival Rabobank had its own issues on Wednesday which prevented customers from requesting loans online, says Reuters.