Citigroup, which is reeling from hefty sub-prime mortgage-related writedowns and losses, has picked the same executive who steered its role in the rescue of collapsed hedge fund Long-Term Capital Management to run a new dedicated sub-prime unit.

Citigroup said in an internal memo that Richard Stuckey will run the sub-prime portfolio group, which will focus solely on managing the bank's assets that have sub-prime mortgage securities as their underlying collateral. Sub-prime mortgages are those given to customers with low credit scores.