You may shout “Wow!” you say to your husband as you hit the brakes on the car. “Did you see the mortgage rate those guys are promoting?” Your troubles are over you may be thinking. You just got to lock in a rate like that for the next decade and you’ve got it made.

Not so fast. That rate may not be the one for you. Commonly, the lowest available rate - and the one that makes the rate sign look great from the street - will be for a variable or adjustable-rate mortgage. This rate has the prospect to be like a roller coaster. The posted variable is the rate you’re getting today and you can’t really predict what kind of ups and downs are ahead of you.

A lender will provide different rates for different kinds of mortgages. The rates are determined based on financial risk- to the institution and to you. When a consumer is willing to meet the risk, then he or she is rewarded with a lower…