Lending transactions would most likely involve the "Layering" phase of the Money Laundering Cycle. This is where a series of transactions helps move the money from the intial "Placement", and after each transaction, the money appears "cleaner."
A very simple scenario involes cash secured loans. The cash was money from the "Placement" phase, and will now secure a loan. The launderer now has a loan proceeds check which he or she then takes to another financial institution to open an account.
The launderer may default on the first loan wherein the bank liquidates the cash collateral to payoff the loan. The launderer doesn't care because you've helped clean the money.
More complex situations involve "straw" buyers, flipping of properties, purchasing properties for way more than market value, etc.
Don't forget Letters of Credit transactions where the launderer may over invoice or under invoice depending on which way the money needs to flow.
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CRCM,CAMS
Regulations are a poor substitute for ethics.
Just sayin'