What happened Shares of Rivian Automotive (NASDAQ: RIVN) declined by 8% on Monday after Ford (NYSE: F) halted its plans to build an electric vehicle (EV) with the upstart automaker. So what Ford took a $500 million stake in Rivian in April 2019. The investment was part of a strategic partnership between the two automakers. At the time, Ford and Rivian planned to jointly create an "all-new, next-generation battery electric vehicle" using Rivian's development platform. "As we continue in our transformation of Ford with new forms of intelligent vehicles and propulsion, this partnership with Rivian brings a fresh approach to both," former Ford CEO Jim Hackett said in a press release announcing the deal. Image source: Getty Images. However, under current CEO James Farley, Ford has prioritized the development of its own electric vehicles, such as its all-electric F-150 pickup truck and Mustang Mach-E sports car. To further that strategy, Ford said late on Friday that it would no longer seek to co-develop a vehicle with Rivian. "We respect Rivian and have had extensive exploratory discussions with them, however, both sides have agreed not to pursue any kind of joint vehicle development or platform sharing," the company said to CNBC. Now what Ford will remain one of Rivian's largest investors. The value of Ford's investment soared along with Rivian's pre-IPO valuation after the EV maker lined up a monster 100,000 vehicle order from e-commerce titan Amazon.com. Rivian's shares then went on to rise even further after its stock market debut on Nov. 10. Even after today's decline, Rivian's stock is up more than 50% from its $78 IPO price. All told, Ford's stake in Rivian is now valued at roughly $12 billion. So, despite the cancellation of its joint development plans, the auto giant will continue to have a vested interest in Rivian's ongoing success. "As Ford has scaled its own EV strategy and demand for Rivian vehicles has grown, we've mutually decided to focus on our own projects and deliveries," Rivian told CNBC. "Our relationship with Ford is an important part of our journey, and Ford remains an investor and ally on our shared path to an electrified future." 10 stocks we like better than Rivian Automotive, Inc.When our award-winning analyst team has a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* They just revealed what they believe are the ten best stocks for investors to buy right now... and Rivian Automotive, Inc. wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of November 10, 2021 John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Joe Tenebruso has the following options: long January 2023 $2,400 calls on Amazon. The Motley Fool owns shares of and recommends Amazon. The Motley Fool recommends the following options: long January 2022 $1,920 calls on Amazon and short January 2022 $1,940 calls on Amazon. The Motley Fool has a disclosure policy.Source