US markets hit record highs after ceasefire extension; ASX set to open lower

US sharemarkets, including the S&P 500 and Nasdaq Composite, closed at fresh record highs on Wednesday (April 22, 2026) following an extension of a ceasefire with Iran. The S&P 500 gained 1.05% and the Nasdaq advanced 1.64%. Despite the positive US market performance, Australian shares are projected to open lower. Oil prices also climbed above US$100 a barrel due to ongoing supply uncertainty in the Strait of Hormuz.