Maturity transformation is part and parcel of what banks do on a daily basis. Many investors are willing to invest on a very short term basis, but many projects require long-term financial commitments. What banks do, then, is borrow short-term, in the form of demand deposits and short-term certificates of deposit, but lend long-term; mortgages, for instance, are frequently repaid over 30 years. By doing this, banks transform debts with very short maturities (deposits) into credits with very long maturities (loans), and collect the difference in the rates as profit. However, they are also exposed to the risk that short-term funding costs may rise much faster than they can recoup through lending.