Shares in chipmaker Nvidia (NVDA) rose more than 4% on Wednesday to close the session at a fresh record high of $154.31 (£122.11) and overtake Microsoft once again to become the world's most valuable company, with a market cap of $3.76tn.

Nvidia has surged more than 14% since its first quarter earnings on 28 May, well ahead of the S&P 500's (^GSPC) 3.4% gain in that time.

The stock has seen a marked turnaround since January, when the release of a cheaper artificial intelligence (AI) model by Chinese startup DeepSeek raised questions about the amount spent on the technology by major US tech firms.

Nvidia, along with other chip stocks, also plunged in April when US president Donald Trump announced sweeping tariffs. In addition, Trump enacted a ban on sales of Nvidia’s H20 chips to China, costing the chipmaker $2.5bn in lost revenue in the first quarter and a projected $8bn loss in the second quarter.

However, in its first quarter results last month, Nvidia posted revenue that beat Wall Street estimates, showing the company continued to perform despite the export controls on its chips to China.

Ahead of those results, Nvidia also announced deals with Saudi Arabia and the United Arab Emirates to supply them with hundreds of thousands of its AI chips.

The latest rise in Nvidia shares comes as investors pile back into tech stocks. Bank of America analysts said in a note Tuesday that tech inflows hit their highest level last week since June 2024.

On the London market, Shell (SHEL.L) was in the spotlight on Thursday morning, after the oil major denied that it is talks to buy rival BP (BP.L).

In a statement to markets on Thursday, Shell said it "has not been actively considering making an offer for BP and confirms it has not made an approach to, and no talks have taken place with, BP with regards to a possible offer."

The company added that it had "no intention of making an offer for BP".

Both Shell and BP shares were little changed on Thursday morning on the back of the statement. The two stocks have fluctuated over the past week with the sharp movements in oil prices due to concerns about disruption to supply, as investors watched developments around the Iran-Israel conflict.

Derren Nathan, head of equity research at Hargreaves Lansdown, said: "Structurally lower oil prices are causing the majors to look at their options, but given Shell's superior asset quality and balance sheet, any combination may be difficult for its shareholders to stomach.