British housebuilder Berkeley Group could lose its spot on the FTSE 100 index after Britain's vote to leave the European Union triggered a sharp decline in shares.

Shares in the London-listed group were down 3% by mid-afternoon on Tuesday (30 August) and have fallen 30% so far this year, and 19% since the EU vote, compared with an average 10% decline on Britain's blue-chip index. The company has also been beset by a number of rating downgrades and target price revisions, with analysts and investors worried over the short-term future of Britain's construction sector post-EU referendum.

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The decline in share price means Berkeley is now the 112th largest UK company by market capitalisation – the parameter used to determine a company's position in the FTSE 100. As a result, the company is expected to lose its spot on London's main benchmark to gold miner Polymetal, when the London Stock Exchange announces its quarterly review on Wednesday.

The changes, however, are not expected to become effective until 19 September.

While the rest of the FTSE 100 has managed to weather the post-Brexit storm, housebuilders have suffered from the uncertainty generated by the vote, given they are more exposed to the British economy than some of their counterparts.

Data released by the Bank of England on Tuesday showed the number of mortgage approvals fell from 64,152 in June to an 18-month low of 60,912 in July, falling short of analysts' expectations of 62,000. By comparison, the first quarter of 2016 total of 216,575 had been the highest quarter for mortgage approvals for house purchases since the fourth quarter of 2007.

"With Brexit uncertainty having driven new buyer enquiries lower in recent months, we suspect thatmortgage approvals have further to fall over the rest of the year," said Scott Bowman, UK economist at Capital Economics.