London (CNN Business) Saudi Aramco shares have slumped to their lowest level since the state oil giant's record-breaking stock market debut, as investors brace for potential Iranian retaliation over last week's killing of the country's most powerful general in a US airstrike.

The stock has dropped roughly 2% since the killing of Quds Force commander Qasem Soleimani, reflecting concerns that Iran could respond to the attack by targeting the oil infrastructure of Saudi Arabia, a key American ally in the region.

Shares have dipped despite a surge in crude oil prices of as much as 6% since Thursday to near $70, which should help boost earnings at the world's most valuable company.

Saudi Aramco shares have been trending lower since the days after the company pulled off the biggest IPO in history in December. The stock's total decline since peaking on December 16 — a week after trading began — briefly topped 10% on Monday, wiping more than $200 billion off the company's market value.

Investors are worried that Iran, which counts Saudi Arabia among its regional foes, could target the company's production facilities or its computer networks in retaliation for the killing of Soleimani.

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