Australian shares tumble as oil hits five-month high

Attacks on Saudi energy infrastructure sent oil prices soaring and Australian shares plummeting. (Bianca De Marchi/AAP PHOTOS)

Australian shares are on track to snap a three-week winning streak as macroeconomic and geopolitical risks put investors on the back foot.

The S&P/ASX200 fell 23.5 points by midday, down 0.27 per cent, to 8769.7, as the broader All Ordinaries dropped 36.7 points, or 0.41 per cent, to 8877.5.