Saudi stocks also fell 9.11 percent, while international bonds issued by Saudi Arabia and Aramco also plunged
Saudi Aramco 2222.SE shares fell 10 percent on Monday after Saudi Arabia slashed its official selling prices for crude and set out plans for a dramatic increase in oil production next month, prompting a sharp drop in prices.
Shares in Aramco were trading at 27 riyals ($7.20), 15.6 percent below its initial public offering (IPO) price of 32 riyals, which in December valued the company at $1.7 trillion in the world's biggest share offering.
Aramco fell below its IPO price on Sunday for the first time since trading began in December when the company's listing was seen as a culmination of years of Crown Prince Mohammed bin Salman's efforts to help diversify the economy away from oil.
Saudi stocks also fell 9.11 percent, while international bonds issued by Saudi Arabia and Aramco also plunged.
Aramco bonds due in 2049 were down more than 8 cents and the state oil giant's bonds due in 2029 were 4.5 cents lower.
Saudi government bonds maturing in 2049 dropped by more than 9 cents, while bonds due in 2029 dropped 3.5 cents.
One-year dollar/riyal forwards, which are trades scheduled to take place a year from now, were at 85 points on Monday, up from Friday's close of 10 points. They hit as high as 182.5 points, topping a high of 181.3 at the end of 2018.
Benchmark Brent LCOc1 crude fell as much as a third following Riyadh's move after Russia balked at making a further steep output cut proposed by OPEC to stabilize oil markets hit by worries over the impact of the coronavirus.
"The Saudi reaction to the breakdown was to revert to the 2014 playbook. By precipitating an oil price collapse they are looking to end their subsidy of higher cost producers," said Akber Khan, head of asset management at Al Rayan Investment.
"This is a painful strategy that requires time to play out and failed on the previous attempt."
Aramco's stock hit an intraday high of 38.70 riyals on its second day of trading but has eased since then on concerns about the valuation, which had kept international funds away from taking part in the IPO.
Arqaam Capital cut its rating of Aramco to hold on Monday, citing the company's significant exposure to the oil price cut which will hit its 2020 earnings. It also cut its target price to 30.80 riyals a share from a previous 39.20 riyals.
It is now forecasting $64 billion net income in the financial year 2020, an estimated 29 percent drop year-on-year, and 38 percent below its earlier estimates.
Aramco, which is set to announce its 2019 earnings on March 16, is expected to post a net profit of 347.6 billion riyals ($92.6 billion) in 2019, according to a mean estimate of 15 analysts polled by Refinitiv, down from $111.1 billion in 2018.