(Bloomberg) — Dip buyers in the dangerous world of long-dated Treasury debt are enjoying a rare pay day — and fast.

Investors over the past week poured $1.8 billion into BlackRock Inc.’s iShares 20 Year Treasury Bond ETF (ticker TLT) — the most among all the 630 ETFs that Bloomberg tracks — just as longer-maturity government bonds sold off on fears over America’s debt trajectory. 

The timing has proved fortuitous. In Tuesday trading, Treasuries rallied — pushing the 30-year yield below 5% — on optimism about trade negotiations between the US and the European Union, and as Japan signaled it may adjust debt sales to stabilize its bond market. TLT jumped 1.7% during the session, on track for its biggest daily rise since February.

It’s a rare win for an ETF trade that has earned a reputation as a so-called widow maker. True to its infamy, TLT has attracted some $49 billion in the past five years despite shedding more than 40% in that time horizon.

“Investors aren’t letting TLT’s widow-maker reputation scare them off,” said Athanasios Psarofagis, ETF analyst at Bloomberg Intelligence. “They’re still buying in, holding on to hope that long-term Treasuries will finally bounce back.”

For some time, bond investors have been demanding extra compensation for the risk of investing in longer-duration debt as Republican lawmakers haggled over President Donald Trump’s signature tax-cut bill that would add trillions of dollars to already bulging budget gaps. Benchmark 30-year Treasury bonds surged above 5.1% last week to trade near the highest in almost two decades. 

But last week’s buying streak in TLT suggests that a growing cohort of traders are betting that yields are high enough to entice buyers and compensate for the risks. Long-maturity bonds are most exposed to interest-rate risk, so they tend to rally the most when borrowing costs fall. 

“Dip-buyers are trying to pick the bottom,” and long-term bonds give investors “the biggest bang for your buck” because they are exposed to the most volatile part of the yield curve, said Byron Anderson, head of fixed income at Laffer Tengler Investments Inc.

The iShares 10-20 Year Treasury Bond ETF (TLH) was also among the ETFs that attracted the most inflows over the past week, along with the iShares 0-3 Month Treasury Bond ETF (SGOV).

Peter Tchir of Academy Securities is among those recommending long-bonds, saying the pessimism is overdone. Adding heft to his belief is the rally in global bonds after Japanese authorities signaled they are considering adjusting their debt plan. 

“The situation wasn’t as bad as the narrative,” said Tchir who recommended investors add duration last week. “Positioning had swung from too bullish to too bearish fairly quickly, too.”

Of course, TLT — which is almost as volatile as US stocks — isn’t for faint hearts. In the options market, traders remain wary of further declines in long bonds. It costs more to buy put options in TLT than to purchase calls, a sign there is demand for downside protection.

“We believe the long end will continue to see term premium increase,” said Lindsay Rosner, head of multi-sector fixed income investing at Goldman Sachs Asset Management. “It’s all about the fiscal, what is the right level to lend at to countries whose balance sheets are trending the way they are.”

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