The S&P/ASX 200 index could retest the 5000-point level if negative momentum continues, according to an analysis of technical levels.

The benchmark was trading about 5180 on Wednesday afternoon, down 0.5 per cent from Tuesday's close. The market has dropped about 4 per cent from late May's highs of 5400, thanks largely to fears Britons could choose to leave the European Union in next week's landmark vote.