How can mortgage originators quote different rates?

Unfortunately, industry advertisers often launch marketing campaigns that offer a low “teaser” interest rate simply to make the phone ring. This unusually low rate may only be available for a specific loan program that fits a small pool of qualified borrowers, but they won't tell you that upfront.
The truth is that mortgage interest rates are not controlled by lenders, and can fluctuate up to several times in any day. Once you understand how rates are determined, you'll feel more comfortable about your mortgage interest rate and the home financing process.
Keep in mind that although loan programs, credit scores and economic factors affect the mortgage interest rate you're offered, the borrower always has the option of paying a one-time, upfront fee to secure a lower interest rate.