We also look at cash in or cash out aggregated over a period of time (6 months to a year) and sort by high to low. Any aggregate amounts that seems out of the ordinary we then look at the individual transactions and try to determine source and/or destination of funds. If it appears suspicious, it is referred to our fraud area for follow-up.
We also look for account abuse (excessive overdrafts, NSF and fee waivers) as these are violations of our internal policies.
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* My opinion is not necessarily that of my employer.