What happened
The yield on the 10 year US Treasury note rose to 4.79 percent on Tuesday, up from 4.73 percent late on Friday, while the 30 year bond stayed at the highest sustained level since 2006. The two year yield reached 4.35 percent. Wall Street followed the bond market down, with the S&P 500 losing 25.62 points, or 0.33 percent, to sit at 7,686.14 by the middle of the New York session, its weakest level since 4 August.
A bond yield is simply the annual return an investor earns for lending money to a government. Yields move in the opposite direction to bond prices, so a rising yield means investors are selling bonds and demanding more compensation to hold that debt. Two forces pushed in the same direction on Tuesday. Brent crude gained 1.7 percent to around 92 dollars a barrel as tensions around the Strait of Hormuz escalated again, and traders cut their bets on how quickly the Federal Reserve will be able to lower interest rates.
The selling was global rather than purely American. UK gilts, Japanese government bonds and euro area sovereign debt all weakened in the same session, and London equities fell alongside New York. Crucially, the damage was concentrated in long dated bonds, which is the classic signature of an inflation scare rather than a fear of recession. When investors worry about growth they buy long bonds. When they worry about prices, they sell them.
Policy rates themselves have not moved. The Federal Reserve holds its benchmark at 3.75 percent, the European Central Bank deposit rate stands at 2.25 percent and the Bank of England Bank Rate is 3.75 percent. None of the three has changed since July. What has changed is the path the market expects from here, and that path is now considerably flatter than it looked a month ago.
Why it matters
Government bond yields are the reference price for almost every other loan in the economy. Banks price fixed rate mortgages off the swap rates that track them. Companies price bond issues and syndicated loans off them. Insurers and pension funds value their liabilities using them. When the 10 year yield moves half a percentage point, the effects reach household budgets within weeks.
For governments the arithmetic is brutal. The United States, the United Kingdom and France all refinance large volumes of maturing debt every year. Each percentage point of extra yield adds billions to annual interest bills, money that cannot then be spent on services or returned through tax cuts. That is why finance ministries watch the long end of the curve as closely as central bankers do.
For share prices, higher yields work in two ways at once. They raise the discount rate applied to future company profits, which mechanically reduces what those profits are worth today. And they offer investors a competing risk free return: when a government bond pays close to 5 percent, the case for owning volatile equities has to be made more forcefully.
There is also a signalling effect. A bond market that refuses to rally even as central banks hold rates steady is telling policymakers that it does not believe inflation is beaten. That makes rate cuts politically and practically harder to deliver.
Explained simply
Government bonds are the tide that every other price floats on. When the tide of yields comes in, mortgages, business loans and share valuations all have to find a new level, whether they want to or not.
Imagine you are deciding where to put your savings. A government offers to borrow your money for ten years and pay you 4.79 percent a year. That is about as safe a return as exists. Every other borrower in the economy, from a homebuyer to a supermarket chain, now has to beat that number to attract your money. The government yield sets the floor, and everything else stacks on top.
Now consider what happens when oil rises sharply. Higher fuel costs feed into transport, food and manufacturing, which lifts inflation. Inflation is the enemy of a fixed income stream, because the 4.79 percent you were promised buys less each year. So investors sell existing bonds until the yield rises far enough to compensate for the new inflation risk. That selling is what happened on Tuesday.
The reason long dated bonds fell hardest is that they are exposed to inflation for the longest. A bond maturing in one year barely cares about prices in 2035. A 30 year bond cares enormously. That is why the 30 year yield reaching 2006 levels is the most telling number in the whole session.
Finally, the reason shares fell is competition. If safe bonds pay more, investors need a bigger reward to hold risky shares instead, and the way markets deliver a bigger future reward is by paying a lower price today.
What it means for you
If you are remortgaging in the next six months, this matters directly. UK five year fixed rates have been sitting close to 4.2 to 4.5 percent for borrowers with meaningful equity. Sustained pressure at the long end of the curve tends to push those quotes up by roughly 0.2 to 0.4 percentage points within a few weeks. On a 250,000 pound mortgage, 0.3 percentage points is about 40 pounds a month. If you have an offer in hand, it is usually worth securing it, since most lenders let you switch down later if rates improve.
Savers get the other side of the trade. Easy access accounts paying around 4 percent and one year fixed bonds near 4.4 percent are more likely to hold their level than fall while yields stay elevated. Cash ISA rates in particular tend to follow the two year part of the curve, which rose to 4.35 percent on Tuesday.
If you hold a pension default fund, check what it owns. Lifestyling strategies shift older savers into long dated bonds automatically, and those funds fall in value when yields rise. A 30 year gilt fund can lose several percent in a week during a selloff like this. That is uncomfortable but not a reason to sell at the bottom, since the same fund now reinvests at a higher yield.
For equity investors, a FTSE 100 tracker is less exposed than a US technology fund, because the London index is weighted towards energy, banks and miners rather than long duration growth companies. Banks in particular tend to benefit from a steeper yield curve.
The bigger picture
The last time 30 year yields sat at these levels for a sustained period was 2006, the year before the financial crisis and the beginning of two decades of extraordinarily cheap money. The world that followed, defined by quantitative easing and near zero rates, may simply have been the exception rather than the rule. Markets are gradually repricing for a normal cost of capital.
What breaks the current pattern is oil. If the Strait of Hormuz reopens and Brent falls back towards the mid 80s, the inflation premium in bonds unwinds quickly and yields could drop half a percentage point in days. If the disruption persists into the autumn, the opposite applies and central banks will find themselves defending rate cuts they no longer feel able to make.
Watch the next US payrolls report and the Bank of England decision on 17 September. Both will tell you whether policymakers are still leaning towards easing, or whether the bond market has already made that decision for them.
