Your lender just offered you a 6.75% rate and wants you to lock it in today. The question that determines whether you overpay by thousands isn't whether rates might drop - it's whether you can actually close before your lock expires.
Rate locks typically cost 0.25-0.50% of your loan amount for every 30 days of protection. On a $400,000 mortgage, a 60-day lock runs $2,000-4,000. If you lock too early and need an extension, add another $1,000-2,000. If you lock too late and rates spike, you could lose your purchase entirely.
The data shows that 30-day locks work for refinances with no complications. For purchases, you want 45 days minimum. New construction? Lock for 6-12 months and negotiate the cost into your builder contract. About 40% of new construction homes close late, and rate lock extensions eat any savings you thought you were getting.
Here's the strategy most mortgage brokers use for themselves: monitor the 10-year Treasury yield daily. When it jumps 0.15% or more in a single day, lock immediately - mortgage rates typically follow within 24-48 hours. If it's trending down gradually, you can usually wait until you have a ratified contract and inspection results.
The worst time to lock is Friday afternoon. Lenders know you're panicking about weekend rate changes and won't negotiate. Tuesday through Thursday mornings give you the best rates and terms. And never lock without getting the exact same quote from at least two other lenders first - you'd be shocked how often a "competitive" rate is 0.375% higher than market.
