With the inside lockup period to sell shares set to expire this weekend, Ford is reportedly selling 8 million of its shares in Rivian, according to sources of CNBC's David Faber.

The Blue Oval currently owns 12 percent of the Amazon-backed EV maker or around 102 million shares. These were acquired before Rivian filed for an Initial Public Offering (IPO) last year. According to the sources, Ford will be selling its 8 million shares through Goldman Sachs.

Following this news, however, shares in Rivian fell 14 percent in mid-day trading, Automotive News reports.

Gallery: Rivian R1T

In line with this, an unknown seller is also reportedly selling a block of 13 million to 15 million Rivian shares, according to Faber. These are handled by JPMorgan Chase & Co. and are priced at $26.90 per share.

The partnership between Ford and Rivian isn't too tight since last year. Both companies reportedly parted ways in terms of EV production, with Ford CEO Jim Farley cited as the source in an interview.

Rivian is facing a slow start in terms of vehicle production during the first three months of 2022. The company has built 2,553 vehicles in Q1 2022, with 1,227 units delivered. Despite that, the California-based EV maker targets to produce 25,000 vehicles this year.

Rivian's production woes come from troubles connected to supply disruptions. That fact translates to stock issues for Rivian, with the company's shares losing half their value during Q1 2022. This was a total reversal of what happened last year when Rivian's shares skyrocketed after going public.

Amazon, which invested more than $1.3 billion in Rivian, reportedly took a $7.6 billion loss after the plunge in the company's stocks. Ford lost $5.4 billion on its Rivian stake.