Gary Lewis, president and CEO of the Bank of Internet USA, had an unusual request from a potential borrower: a $400,000 loan that would completely pay off his home in five years. No problem. "That doesn't fit into any cookie cutter loan that's out there. It was like a five-year, $400,000 car loan," explained Lewis. "His monthly payment was $20,000, but it was a great loan that was lower than the rate on a 30-year fixed mortgage. This guy couldn't get a loan anywhere." Bank of Internet USA was able to make the loan because it is a portfolio lender, which means it keeps loans it makes instead of reselling them on the secondary market. Usually, banks bundle loans together in the form of securities, reselling them to raise capital to make more loans and help hedge risks associated with default. But in order to securitize loans and sell them to buyers like Fannie Mae ( FNM) and Freddie Mac ( FRM), the loans involved must be standardized. As a result, the wide majority of loans sold on the secondary market are plain-vanilla 30-year fixed-rate and one-year adjustable-rate mortgages. Since most portfolio lenders resell every loan they make, few were flexible enough to create that five-year, $400,000 car loan. Sounds great. What's the rub? Homeowners must be willing to pin their mortgage to adjustible rates, since that's how these lenders make money. While these rates are competitive, they may be a bit higher than fixed rates -- you pay for flexibility. But borrowers with special requests, bigger loans and/or shorter time frames to stay in their homes should consider portfolio lenders.