The yield for the longest-dated Treasury bond fell to its lowest level in history.

Investors said the $22 trillion U.S. government debt market hit this key milestone on a combination of factors including the growing world of negative-yielding government bonds, expectations for Fed easing spurred by rising recession concerns, and the absence of inflation pressures.

The 30-year Treasury bond yield TMUBMUSD30Y, 1.403% fell to 2.06% on Wednesday, following a relentless rally in long-term government bonds in the past few weeks. The 30-year yield pushed below its previous all-time low set in July 2016, when it touched 2.09% after the U.K. voted to leave the European Union. Debt prices move in the opposite direction of yields.

The rate for the so-called long bond had risen to a multiyear peak of 3.46% in November, but has steadily retreated since the U.S. central bank reversed its plans to push for rate hikes and later cut interest rates in July.

The 30-year Treasury bond yield is near an all-time low Bloomberg

The more widely-watched 10-year note yield TMUBMUSD10Y, 0.657% is still around 35 basis points away from its all-time low hit in July 2016, when it fell to 1.27% in July 2016.

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Rising prices for long-term bonds comes as inflation expectations have retreated sharply across survey-based measures, such as the University of Michigan consumer sentiment survey and market-based measures derived from the Treasury inflation-protected securities (TIPs).

The 10-year breakeven rate, or where traders of TIPs TIP, +0.13% anticipate consumer prices will trend over the next decade, stood at 1.63% on Wednesday.

Longer-term bonds are more sensitive to the corrosive impact of inflation than their shorter-term peers, so higher values for extended maturity debt can reflect expectations for price pressures to stay cool.

Analysts said growing doubts about the U.S. central bank’s ability to hit its inflation target could also make it even more difficult to achieve it in the future, a problem now faced by the Bank of Japan and the European Central Bank.

“The Fed is at risk of having to fight an unanchored inflation expectation situation,” Vinay Pande, head of trading strategies at UBS Global Wealth Management, told MarketWatch.

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Jonathan Hill, an interest-rate strategist at BMO Capital Markets, also feared the 30-year yield’s decline was underlining intensifying growth concerns as trade tensions show few signs of waning.

He pointed to how the inflation-adjusted yield, or the real yield, for the 30-year bond was near its lowest levels since 2013. Real interest rates are seen as a true indicator of the cost of funds for a borrower, and tend to fall during periods of economic pessimism.

The depressed level of real yields “speak volumes as to market expectations for diminished global growth in coming decades,” he said in e-mailed comments.

Hill added that near record low yields on 30-year Treasuries could also point to expectations for lower interest rates to remain a firming reality for the bond-market, along with potential expectations for the U.S. central bank to restart its asset purchases program if the economy experienced a downturn.

The rally in the long bond also reflects the insatiable appetite for U.S. debt from foreign investors.

Pande said liability-driven investors like pension funds and insurance companies in Japan and Europe that needed to match their investments to the extended timeline of payments to their members had few sources of positive-yielding income, and were being forced out of their own domestic bond markets.

This has become a particularly pressing issue as a broader swathe of global bond markets now sports negative yields, which means investors will lose money if they hold the security for the lifetime of its existence. The universe of negative-yielding bonds increased to $15 billion last week, according to RBC Global Asset Management.

“There’s really only one place where you can get relatively high, positive yields for risk-free assets,” said Pande, referring to U.S. Treasuries.

Though European and Japanese investors are faced with lofty hedging costs when buying dollar-denominated bonds, many chose to risk buying U.S. government debt without hedging against the risk of currency fluctuations, he said.