How fast will this prepayment retire my mortgage?

Mortgage rates fluctuate from day to day, depending on a number of factors related to the economy and to choices made by investors. While some mortgage money comes from deposits held by banks and credit unions, most of the funds for borrowers come from investors in capital markets.

Mortgage rates are influenced by a variety of factors, rather than moving in lockstep with any one economic indicator. The stock market rises and falls for a wide variety of reasons, including global, economic and political issues, but as a broad rule of thumb, a rising stock market indicates optimism among investors about the economy.

For the most part, this is a discussion about time. You should compare the total costs of the difference in the two interest rates over your given time horizon.