What happened

After a sharp drop yesterday, the stock of Rivian Automotive (RIVN -1.60%) accelerated its slide on Thursday. This week alone, shares of Rivian have plummeted more than 20%. That includes a double-digit drop today, with the stock down 10% as of 10:30 a.m. ET.

So what

Before today, the stock's decline came with general market sentiment that has gone against high-flying aggressive growth stocks recently. But today's swoon comes from nervous investors who may be questioning what has been thought of as one of Rivian's biggest advantages: its relationship with Amazon

Rivian R1T pickup truck in the wilderness with two owners.

A Rivian R1T pickup. Image source: Rivian Automotive.

That nervousness came with news that Amazon will also be partnering with Chrysler parent Stellantis to be the first commercial customer for its Ram ProMaster electric delivery vehicle, as reported by Reuters.

Now what

Amazon was an early investor in Rivian, and has placed an initial order for up to 100,000 delivery vans from the company. An Amazon spokesman told financial news network CNBC that its relationship with Rivian hasn't changed, stating in an email: "We always knew that our ambitious sustainability goals in our last mile operations would require multiple electric delivery van providers. ... We continue to be excited about our relationship with Rivian, and this doesn't change anything about our investment, collaboration, or order size and timing."

But that wasn't enough to keep investors from running scared. That shouldn't be unexpected with an aggressive growth stock that has a market cap of almost $75 billion with virtually no revenue as of yet. This kind of volatility is something Rivian investors will need to become comfortable with as the long-term story plays out.