Ford sold 7 million shares for about $188.2 million, or $26.88 apiece, according to a regulatory filing on Friday.
The sale reduces the shares Ford holds to 86.9 million.
On Tuesday, Ford had sold about 8 million shares of Rivian worth $214 million.
Initial investors in Rivian's initial public offering were able to sell shares this week as the IPO lockup period expired.
Rivian went public on Nov. 10 at $78 a share. Shares even rose as high as $179 a few days later.
Rivian shares closed at $26.70 on Friday.
Ford reported a net loss of $3.1 billion in the first quarter, driven by a steep loss in valuation of its Rivian stake.
Ford said it suffered a $5.4 billion mark-to-market loss on its investment.
|F||FORD MOTOR CO.||12.43||-0.40||-3.15%|
|RIVN||RIVIAN AUTOMOTIVE INC.||26.53||-1.46||-5.22%|
Among Rivian's competition is Ford's F-150 Lightning electric pickup truck.
In addition, the company is dealing with a supply chain crisis that has impacted production.
The electric-car maker had slashed its planned 2022 production in half to 25,000 vehicles.
Reuters contributed to this report.