Expedia on how one extra data field can cost $12m

Summary: on their checkout page, they had an optional "Company" field under the "Name" field. This confused some people, who thought they were being asked for the company that issued their credit card, so they would put their bank name in that field, and then go on to fill out the address fields WITH THE ADDRESS OF THEIR BANK instead of their own address! This caused the address verification to fail on the credit card transaction. By taking out the "Company" field, $12m/year in transactions that would have failed now succeed.