(Bloomberg) -- Investors are fleeing the biggest exchange-traded fund focused on domestic U.K. stocks, lending credence to Goldman Sachs Group Inc.’s warning that the shares are most sensitive to economic risks from Brexit and pound volatility.

The Vanguard FTSE 250 UCITS ETF that tracks the benchmark index for U.K. mid-cap shares saw an outflow of 89 million pounds ($108 million) in the latest trading session that Bloomberg has data for, its biggest one-day redemption since January.

Tensions between British and European Union negotiators came to a head this week, fueling concern that a hard Brexit will be another blow to an economy already ravaged by the coronavirus pandemic. A no-deal end to the transition period would hit U.K. domestic stocks most of all, Goldman strategists led by Sharon Bell wrote on Thursday.

The coronavirus crisis and resulting lockdown have plunged the U.K. economy into a recession, fueling fears that even after the restrictions are lifted, many businesses like retailers and transport providers might incur long-term damage as consumers scale back spending and travel.

The domestic-focused FTSE 250 Index of midcaps tends to be more sensitive to internal economic trends than the larger FTSE 100 Index. Within such shares, Goldman strategists highlight homebuilders and banks as especially vulnerable to policy uncertainty and pound volatility.

The FTSE 250 has been outperforming its large-cap counterpart since the market began rebounding in late March. Goldman says that this is due to the FTSE 250 lacking oil companies, which have suffered as the commodity’s price slumped.

“From here, if oil prices continue to rise from their recent lows - as global demand improves and supply is curtailed - and if the U.K.-EU negotiations remain at a roadblock, we think U.K. domestic stocks and FTSE 250 are at greater risk, especially given neither trade on a substantial discount,” said Goldman strategists.

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