Investors will consider hoarding cash in vaults as government bond yields fall deeper into negative territory following the U.K.’s vote to leave the European Union, according to Talanx AG, Germany’s third-biggest insurer.

“Storing physical cash as an alternative to paying negative interest rates does look increasingly attractive,” Chief Financial Officer Immo Querner said in an interview.

The aftershocks of the U.K.’s vote to leave the EU continue to reverberate across financial markets, with the pound extending its sell-off near a 31-year low and yields on 10-year German government bonds dropping to minus 0.08 percent on Monday.

The global mountain of negative-yielding sovereign debt swelled to more than $10 trillion before the Brexit decision.

“The negative-yield terrain now spreads toward 10-year maturities,” Querner said. “So at some point, one may also be talking about the incentives of storing cash for medium-term euro-assets.”

The aftershocks of #Brexit continue to reverberate, with the Dow down more than 300 points https://t.co/zeDB65TL8T pic.twitter.com/VFS9UM1wtQ — Bloomberg (@business) June 27, 2016

Talanx had 102 billion euros ($113 billion) of investments at the end of March, with 90 percent in fixed-income assets such as government, covered and corporate bonds. Investment income is being squeezed by low interest rates and to help cushion the impact, the Hanover, Germany-based insurer has invested in alternative assets such as renewable energy and infrastructure where returns are typically higher.

Other financial institutions have also tested or considered storing physical cash as an alternative to paying negative interest rates. Nikolaus von Bomhard, Munich Re’s chief executive officer, said in March that the reinsurer will store at least 10 million euros in two currencies so it won’t have to pay for the right to access the money at short notice. Allianz SE, Europe’s biggest insurer, considered the move but so far has decided against it.

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