UK borrowers sometimes find their mortgage quotes rising even when nothing has changed at the Bank of England. One reason is that UK government bond yields often follow US Treasury yields. When American borrowing costs jump, gilts tend to follow, and that can feed through to the rates British households and businesses pay. This week’s sell-off in US bonds, after a weak 30-year auction, is a good example of the link in action.
Gilts and Treasuries in brief
Gilts are bonds issued by the UK government; Treasuries are bonds issued by the US government. Their yields show how much it costs each government to borrow. They also act as benchmarks for many other borrowing costs, from mortgages to corporate loans. Our guide to the 30-year gilt covers the UK side in more detail.
Why the US sets the tone
The US Treasury market is the largest and most traded bond market in the world. It is the global reference point for what a safe return looks like. When Treasury yields rise, investors around the world can earn more by holding US government debt, so other bonds need to offer higher yields to stay attractive.
Many large investors, such as pension funds and global bond funds, hold both gilts and Treasuries. When they sell Treasuries, they often sell other government bonds at the same time, pushing yields up across markets.
The channels that connect them
There are several links. Inflation expectations are one: if US data suggests inflation is proving persistent, investors may worry the same is true elsewhere, especially when energy prices are a shared driver. Central bank expectations are another: a more aggressive Federal Reserve can lead markets to expect other central banks, including the Bank of England, to keep rates higher too.
The so-called term premium matters as well. This is the extra return investors demand for lending for longer periods. When it rises in the US, perhaps because of concerns about government borrowing, it often rises globally.
When the link weakens
The connection is strong, but not perfect. UK-specific news can push gilts in their own direction. A surprise move or change in tone from the Bank of England, UK inflation data or concerns about UK government finances, as in the 2022 mini-budget crisis, can all cause gilts to move independently. Over longer periods, differences in each country’s economy and inflation tend to matter more.
What it means for mortgages and sterling
UK fixed-rate mortgages are priced largely from swap rates, which closely follow gilt yields. So when Treasuries pull gilt yields higher, lenders may raise the cost of new fixed-rate deals, even without any change in Bank Rate. Our guide to mortgage rate pass-through from Treasury yields explains the chain.
For sterling, the effect depends on the gap between UK and US yields. If US yields rise faster than gilt yields, the dollar often strengthens against the pound. If gilt yields rise faster, the pound may hold up better.
How traders use it
Traders often watch the US 10-year yield during the UK afternoon, especially around major US data releases, to anticipate moves in gilts. They also watch the spread between the two, the difference in yield, as a gauge of how much UK-specific risk the market is pricing.
A beginner’s takeaway
US Treasury yields act as the global anchor for borrowing costs, so when they rise, UK gilt yields often follow. That can affect mortgages, company borrowing and the pound. Keep an eye on the US 10-year yield even if you only trade UK markets; it is often the first place a change in direction shows up.
If you want to see how well your trading approach handles moves in rates and bonds, take our free Trader Assessment and get a clear view of where to improve.
