The world’s biggest bond investors are leaving themselves with almost no room for error.

More than $2.5 trillion of euro-area government debt all but guarantee losses for buyers. Traders are ramping up wagers on a selloff in German bunds as 10-year yields approach April’s record lows. And jitters in the market are at levels last seen during the stunning rout in European debt markets a year ago.

Yet JPMorgan Asset Management, Standard Life Investments and Lombard Odier Asset Management all say there’s no reason to fear a violent reversal. Last time around, bond investors who pushed yields to such low levels suffered staggering losses as the European Central Bank’s quantitative easing spurred a glimmer of optimism in the region’s economy.

There’s little of that now. Despite negative interest rates and more than $660 billion in central-bank bond buying, the prospects for euro-area growth and inflation have only gotten worse. So whatever actions ECB officials decide to take at their meeting this week, many of those same investors are confident President Mario Draghi will have no choice but to press for even more aggressive measures in the weeks and months to come. And that will keep even negative-yielding bonds in demand.

Selloff Risk

“There’s always a risk of a selloff” like in 2015, said Jack Kelly, an Edinburgh-based money manager at Standard Life, which oversees about $360 billion. But, “we have a high conviction that the ECB will act. There needs to be a sense of urgency. Draghi fully understands the need to convince the market.”

Any selloff would be an opportunity to buy, Kelly said.

Getting it wrong could be disastrous, especially if last year’s experience is any guide. After average yields on euro-area sovereign debt fell to a record-low 0.425 percent a year ago, the most bullish bond buyers were run over.

Across the region, sovereign bonds lost more than 400 billion euros ($440 billion) in value during a two-month selloff that ended in June, data compiled by Bank of America Corp. show. Holders of longer-term German debt lost a record 13 percent in the second quarter alone, while bond markets in Asia and the U.S. were also upended by the fallout.

And because yields are so low, even mild disappointments can lead to big declines. After the ECB’s December meeting failed to inspire investors looking for bolder measures, euro government debt suffered the biggest single-day loss on record.