Australian shares are set for a virtually unchanged open, with futures pointing to a gain of just 1 point at the start of trade. The flat lead comes as oil prices tumbled below $US80 per barrel for the first time since early March, with Brent crude falling 5.4% to $US78.69. Markets are digesting optimism about a tentative US-Iran deal that could reopen the Strait of Hormuz, though significant hurdles remain in negotiations.

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