The old ones are the best
Computer fraud is as old as computers. Take computer fraud to mean the illegal moving of money through bank accounts via a computer's overnight jobs and the processing of individual computer records ( as happened in this case ).
The 'original' computer fraud job goes back to the time when rounding was a new idea in computing terms ( COBOL ? ). The question about this story is whether it actually happened or is it an urban myth ?
Seems a programmer rewrote a bank system so that any rounding done by the system benefitted him personally. So interest is calculated for an account and if said interest includes a fraction of a penny then that is NOT added to the account in question but sent to the programmer's account.
So the calculation says the interest is £31.735p but the account only receives £31.73p with the extra ha'penny credited to the programmer's account. A trivial sum, even back then, but when it happens literally tens of thousands of times then the money stolen does add up.