About an hour and a half after the opening bell, the Dow Jones Industrial Average was up 0.5 percent, the broad S&P 500 index was up 1 percent and the tech-heavy Nasdaq Composite was up 1.3 percent.
Oil futures rose sharply last week to their highest levels in months following attacks on Saudi Arabia by the Iran-backed Houthi movement in Yemen.
On Monday, prices retreated, with a barrel of North Sea crude (Brent) costing $115.08 after falling 1.4 percent during the day.
Several major technology companies with strong ties to AI - such as Nvidia, Micron, Broadcom and AMD - were posting solid gains. This follows AI company Anthropic's application to list on the Nasdaq stock exchange, with an expected very high valuation.
