Rivian edges closer to an I.P.O., seeking a valuation above $50 billion.

Rivian, an electric truck maker backed by Amazon and Ford Motor, is aiming to be valued above $50 billion in its initial public offering next week.

The company updated its registration documents with the Securities and Exchange Commission on Monday to say it was aiming to sell 135 million Class A common shares priced between $57 and $62 a share, raising up to $8.4 billion.

Rivian is one of many start-ups hoping to capture a share of the electric vehicle market, which is expected to grow exponentially over the next two decades. The company is chasing Tesla, the leader in the field. Tesla recently topped $1 trillion in value, and it made its first full-year profit last year.

Amazon has invested over $1.8 billion in Rivian, and it disclosed last week that it held a 20 percent stake in the company. Amazon, which has been building up its own delivery operation, has a contract to buy 100,000 delivery vehicles from Rivian.

Founded in 2009, Rivian makes an upscale pickup truck and a sport-utility vehicle, both designed to be driven off-road. “Keep the world adventurous forever,” the company proclaims in its I.P.O. filing.

If underwriters make use of their ability to sell extra shares — an overallotment option known as “greenshoe” — the company’s fully diluted value could reach $61 billion, said Matthew Kennedy, a senior I.P.O. market strategist at Renaissance Capital.

Rivian first published its papers to go public in August, then aiming for a valuation of around $70 billion. Rivian has lost $2 billion since the start of last year, underscoring the costs and risks of developing electric vehicles. It expects to spend roughly $8 billion on facilities and equipment through the end of 2023.

Peter Eavis contributed reporting.