Why Mortgage Rates Change During the Day
Mortgage rates aren't set by the Fed and they don't change once a day — they move with mortgage-backed securities in real time. Here's what's actually happening behind the rate quote.
If you've ever gotten a rate quote in the morning and a different one in the afternoon, you weren't imagining it. Mortgage rates change during the day — sometimes two or three times — and the reason is simpler than most lenders bother to explain.
Mortgage rates aren't set by the Fed
This is the most common misconception. The Fed sets the federal funds rate, which influences short-term rates (credit cards, HELOCs, auto loans). Mortgage rates follow the 10-year Treasury yield and — more directly — mortgage-backed securities (MBS), which trade like bonds.
When MBS prices go up, mortgage rates go down. When MBS prices fall, mortgage rates go up. Both happen continuously, all day, every weekday the bond market is open.
So the question isn't "did the Fed change rates today?" It's "what did the bond market do at 10:47am?"
How lenders price the day
Wholesale lenders publish a rate sheet each morning, usually between 8:30 and 10:00 Pacific. The sheet is a grid: rate options crossed with point/credit cost, filtered by loan type, FICO, LTV, and lock period.
The morning sheet reflects yesterday's market close plus an overnight risk buffer. The lender's pricing desk watches MBS prices in real time and decides whether the sheet still makes sense.
If MBS sells off hard during the day — say, after a hot inflation print at 8:30am Eastern — the lender's morning rates suddenly underprice the new risk. They have two choices: take the loss, or reprice for the worse.
"Reprice for the worse" emails
If you've ever locked at noon and then heard from your broker that the lender repriced 45 minutes later, this is what happened. The lender pulled the morning sheet, published a new one at higher rates, and any quote not yet locked at the old sheet is now invalid.
On a volatile day, lenders can reprice for the worse 2-3 times. On a quiet day, the morning sheet sticks until close.
The reverse — "reprice for the better" — happens too but is less common. Lenders are slower to pass along improvements than deterioration, because they don't want a day full of locks that hurt their hedge if MBS reverses.
What brokers see vs what borrowers see
Brokers get the wholesale rate sheets directly, often with a market-tracker feed (MBS Live, Mortgage News Daily, etc.) showing what MBS has done since the morning sheet went live. We can see in real time when a reprice is likely.
That's why your broker might say "let's hold off 30 minutes" or conversely "let's lock in the next 10 minutes" — we're reading the same MBS chart the pricing desk is reading.
Retail lenders typically don't show their pricing publicly and don't share the underlying market move. The borrower sees one quote in the morning, a different one in the afternoon, and no explanation.
What this means for your loan
A few practical takeaways:
1. A "verbal quote" from yesterday is worthless today. Always confirm pricing the day you intend to lock. 2. Locks are timestamped. The lender's lock confirmation will list the exact time. If you say "lock me" at 1:47pm and the reprice hit at 1:35pm, you're getting the new sheet. 3. CPI mornings and FOMC days are volatile. Avoid locking 30 minutes before either release if you have the flexibility. Either lock right before with an idea of the risk, or wait until the dust settles by mid-afternoon. 4. Friday afternoons can move oddly. The bond market thins out, and lenders sometimes reprice defensively before the weekend.
A real example from this year
In March, the morning rate sheet came out at 6.625% for our standard scenario (780 FICO, 70% LTV, $806,500 loan). A weak jobs report hit at 5:30am Pacific, MBS rallied, and the lender repriced for the better at 9:15am — 6.50% on the same scenario. Two borrowers I had teed up that morning saved $50/month each because we waited 20 minutes to lock.
The flip side happened in May. We locked at 6.50% at 10:12am. By 11:30am, after a Fed-speaker headline, MBS sold off and the lender repriced to 6.625%. The borrower we locked saved 0.125% by acting in time. The other borrower we were waiting on — who wanted to "think about it overnight" — locked the next day at 6.625%.
Bottom line
Mortgage rates move all day because they're priced off a market that trades all day. The morning rate isn't "the rate" — it's the morning rate. If you're getting close to a lock decision, work with a broker who watches the market in real time, not one who quotes you yesterday's number and hopes for the best.
Want a real-time read on where rates are right now for your specific scenario? Run a free quote — we'll send you the current rate sheet, not yesterday's.