A sell-off in Europe's bond markets may sound distant from day-to-day household finances, but it could affect the cost of mortgages and other loans, as well as how much governments can spend on public services.
Mortgage rates have started rising in Germany and Italy, two of Europe's four biggest economies.
However, mortgage rates in Italy do not necessarily follow government bond yields directly — they tend to track euro interest-rate swaps more closely, though the two often move in tandem since both reflect the wider interest-rate outlook.
Overall, higher government borrowing costs are likely to translate into higher borrowing costs for the private sector, as sovereign yields are typically used as a reference rate.
According to Robert Timper, BCA's chief fixed income strategist, the monetary policy outlook remains the main driver of government and private-sector borrowing costs.
European government bonds came under significant selling pressure at the beginning of the week, with France's 10-year bond yield hitting a 17-year high and Germany's 10-year Bund yield reaching its highest level since 2011 on Tuesday.
On Thursday morning, France's 10-year OAT yield was still above 4.10%, the highest in the eurozone, while Italy's had eased to 4.06% and Spain's stood at 3.69%. The benchmark German 10-year Bund yield was slightly above 3.25%.
The sell-off came as hopes of a swift resolution to the Iran conflict faded, pushing oil prices and inflation expectations higher.
According to Timper, ever since "shipping through the Strait of Hormuz has been disrupted, European bond yields have been highly sensitive to energy prices."
He added that "while oil prices were the main driver early in the conflict, in recent weeks, natural gas prices have increasingly contributed to upward inflation pressures, which in turn are pushing yields higher."
European natural gas prices have more than doubled this year. Dutch TTF futures, Europe's main gas benchmark, rose from €29 to €63.80 per megawatt-hour between the start of the year and 20 August.
European gas prices hit highest point since March, worse may follow
"The market anticipates more ECB rate hikes," Ioannis Sokos, a strategist at Deutsche Bank Research, told Euronews Business.
He added that the anticipated three-month interest rate for December 2027 has risen by 12 basis points since last Thursday, indicating that investors now expect more ECB rate increases.
Governments have also resumed issuing bonds after the summer lull, adding to the supply of debt.
Government bond yields and mortgage rates are influenced by the same broader forces— particularly inflation expectations and expected ECB policy — but the direct connection differs between countries.
In Germany, mortgage rates are strongly connected to Bund yields.
German mortgage broker Interhyp AG told Euronews Business that the 20-year fixed mortgage rates are expected to rise by seven basis points over the following week from the average rate of 4.32% on Thursday.
According to another mortgage broker, Dr Klein Privatkunden AG, some banks have already increased rates.
"Some banks reprice their mortgage rates on a daily basis and therefore track developments in the capital markets very closely. These banks are already offering higher rates, and borrowers often have only two to three days to secure an offer at the previous conditions," Florian Pfaffinger, a member of the Expert Council at the firm, told Euronews Business.
Pfaffinger added that banks using fixed rate grids have also partly adjusted their rates, "while we expect others to follow over the next few days".
While each offer is individual and can change quickly, the firm said mortgage rate adjustments at many banks were broadly in line with changes in German Bund yields.
However, several other factors affect the size of the adjustment, including changes in bank margins and capacity management.
The 10-year Bund yield rose from around 2.85% on 26 June to 3.26% on 20 August.
In France, where the 10-year bond yield is the highest in the eurozone, above 4.1%, the increase has not yet been passed on.
According to Pretto, a French mortgage brokerage, the average mortgage rate for a 20-year loan is around 3% to 3.5%, while another firm, Cafpi, listed an average rate of 3.31% on Thursday morning.
Mortgage rates in France primarily follow the European Central Bank's deposit rate. However, the 10-year government bond yield has historically also played a role in determining borrowing rates.
Historically, increases in French government bond yields have gradually fed through to other borrowing costs. A 2021 Banque de France study estimated that a sustained one-percentage-point rise in sovereign yields could raise borrowing rates by 0.1 percentage points after three months and 0.78 percentage points after two years.
However, Pierre Chapon, co-founder of mortgage broker Pretto, said this relationship has weakened since early 2025. Record household savings have given well-funded banks a cheaper source of money, allowing them to price mortgages more closely in line with ECB rates than French government bond yields.
Chapon said higher sovereign yields have not yet affected French mortgage rates.
"We don't see an impact on mortgage rates yet, but it could come. Given part of the bond yield increase is linked to inflation anticipation, if this situation lasts, then ECB rates could go up, and this will impact mortgage rates by 10-20 basis points."
The ECB's next interest-rate decision is due on 10 September, followed by another meeting on 29 October.
ECB hostage to oil prices? Lagarde leaves door open for a September hike
ECB holds rates at 2.25% as the reignited Iran war keeps a second hike in play
In Italy, mortgages could see a wider repricing within weeks, according to a mortgage broker.
A spokesperson for MutuiOnline.it confirmed that average rates for 20-year fixed mortgages across all types were 3.50% on Tuesday, after some smaller banks had increased rates in early August.
Traditionally, fixed-rate mortgages in Italy track euro interest-rate swaps more closely than government bond yields. However, Italian government bond yields and euro swap rates often move in the same direction because both reflect the wider interest-rate outlook.
Italian 10-year bond yields rose from 3.86% on 4 August to 4.08% on 20 August.
"We are already seeing some early signs of repricing. In the first half of August, three smaller banks increased their mortgage rates. We would expect additional adjustments if the recent increase in market rates proves persistent, although repricing may be slower during the mid-August holiday period," the firm said.
If swap rates remain elevated, mortgage offers could rise within weeks, potentially pushing average 20-year rates above 3.5%. However, the increase will depend on how much of the higher cost banks pass on to customers.
In Spain, mortgage pricing responds more directly to ECB rates. After the central bank raised its deposit rate from 2% to 2.25%, some banks increased their mortgage rates by between 0.2 and 0.5 percentage points in the following weeks, according to Spanish mortgage brokerage iAhorro.
Spokesperson Laura Martinez cited the latest official data, showing that the average rate on fixed-rate mortgages signed in May was 2.96%. She added that brokerages can achieve significantly lower rates.
A further rate rise is expected at one of the ECB's upcoming meetings, either in September or October.
"If the ECB raises rates, mortgage rates will likely rise as well, but we don't expect major increases since we're approaching the end of the year and banks need to meet their sales targets," Martinez added.
Europe's biggest economies are heavily indebted.
France had the largest debt pile among the four countries in 2025, at an estimated $3.9tn (€3.3tn), followed by Italy at $3.5tn (€3tn), Germany at $3.2tn (€2.7tn) and Spain at $1.9tn (€1.6tn), according to the IMF.
Debt-servicing costs are expected to rise if long-term yields remain elevated, but the effect will filter through gradually. Existing bonds continue paying their original interest rates until they mature. Governments face higher costs when they refinance maturing debt or undertake new borrowing at current market rates.
"At the moment the average coupon of the entire stock of bonds of these countries is significantly below current market yields. The longer we stay in this higher yield environment, the larger the part of debt which will be refinanced under these higher yields," Sokos said.
He estimates that annual gross financing needs — including maturing debt and new borrowing — amount to around 24% of GDP in Italy, 21% in France and 15% in both Germany and Spain, based on ECB data.
As a share of GDP, interest expense is expected to remain highest in Italy for the foreseeable future, according to BCA. However, France will see the largest increase, with its interest bill forecast to double by 2031.
Sokos said, "France and Italy are more vulnerable than Spain and Germany." He added that Italy has a larger debt-to-GDP ratio but a lower budget deficit and a history of primary surpluses, coupled with a better external position than France.
"France on the other hand, has a larger deficit and political uncertainty with respect to how to bring down this deficit."
Higher interest expenditure does not automatically produce an identifiable tax rise, but more government revenue must be used to service debt, leaving less fiscal room for public services, investment, benefits or tax reductions.
Asked at what level government bond yields would begin to create a more serious fiscal sustainability problem for France, Italy or other highly indebted European economies, Timper said high yields are not necessarily dangerous if they reflect stronger growth and inflation, which can also increase tax revenue and nominal GDP.
The more serious danger arises when investors demand higher yields because they doubt a government's ability to control its debt. That risk premium raises the interest bill, worsens the public finances and can lead investors to demand an even higher premium.