12 CFR 7.2019 outlines the kinds of agreements, including the taking of own bank stock as collateral, a national bank may enter into. However, it applies only to national banks.
If there are limitations on the taking of other bank stock as collateral, they would appear in state law. I am not waware of any Maryland law which would place limits on taking someone else's stock as collateral.
Depending on the size and nature of the loan and the stock held, Regulation U may require certain disclosures of the borrower.
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Opinions expressed are not necessarily those of my employer.
Paul Brinker CRCM
Director, Corporate Compliance
First National Bank of Omaha
402-964-8313