Long-dated U.K. borrowing costs hit a level last seen in 1998, and European stocks slid as the pressure spread from Treasuries to London, Paris and Tokyo.
The selloff in long-term government debt crossed the Atlantic overnight and found its sharpest expression in London.
The yield on Britain's 30-year gilt climbed above 6% on Thursday for the first time since 1998, touching about 6.07%. U.K. stocks followed bonds lower, with the FTSE 100 down 1.7% in morning trading. Germany's DAX and France's CAC 40 each fell 1.3%.
London now pays more than Washington
The comparison with the United States is telling. Treasury's 30-year bond yielded 5.64% at Wednesday's close. At 6.07%, Britain is paying roughly 43 basis points more than the U.S. to borrow for three decades, even though American yields themselves sit near their highest levels in more than two decades.
The domestic backdrop is fiscal. Chancellor John Healey faces his first Budget later this month, and the gilt market is effectively setting the terms of that statement in advance. Every additional basis point on long-dated borrowing raises the cost of the government's financing plans and narrows the room for spending or tax decisions.
Europe's own fault line
France is under similar strain. The 10-year French government bond yielded 4.85% on Wednesday, and its premium over German Bunds widened 5.9 basis points to 117.1. That spread implies a 10-year Bund yield of about 3.68%. French yields rose 60 basis points in September alone and posted their largest quarterly jump since 1987.
In Asia, Japan's 10-year yield rose 4 basis points to 3.11%, adding Tokyo to the list of markets moving in the same direction. Indian government bonds also slid.
Contagion or common cause?
The move invites two explanations. One is contagion: the sharp rise in U.S. Treasury yields is being exported to other markets through global portfolio rebalancing and a stronger dollar, which reached a 14-week high near 101.61. The other is that each market is wrestling with its own version of the same problem, large deficits and sticky inflation, and the synchronized timing reflects common conditions rather than a single source.
The distinction matters for investors. If contagion dominates, a calmer U.S. payrolls report on Friday could pull global yields back together. If domestic fiscal concerns dominate, London and Paris could stay under pressure even if Treasuries stabilize.
What to watch
The spread between 30-year gilts and 30-year Treasuries is the cleanest gauge. A narrowing would suggest the U.S. was driving the move. A gap that holds or widens would put the focus squarely on Britain's own Budget, due later in October.