Rocket Lab (NASDAQ: RKLB) has delivered extraordinary returns for early investors, turning a modest $5,000 stake into approximately $37,810 over the past five years.

Five years ago, Rocket Lab shares traded just above $10.60, a figure that looks almost unrecognizable compared to where the stock sits today at around $80.

That price appreciation translates to a gain of more than 650%, a performance that has outpaced the vast majority of publicly traded companies over the same period.

The space industry has expanded rapidly in recent years, providing Rocket Lab with a growing addressable market and fueling investor enthusiasm for the company’s long-term prospects.

Rocket Lab recently reported a record backlog of $2.36 billion, a figure that underscores the genuine commercial demand for its launch and spacecraft services.

Despite the impressive backlog, there are serious valuation concerns that investors cannot afford to ignore as the stock continues its meteoric rise.

The stock currently trades at more than 60 times its annual sales, a premium multiple that leaves little room for operational missteps or delays in execution.

Cash burn is another pressing concern, with Rocket Lab’s free cash flow coming in at more than $270 million in the most recent year, a significant drain on its balance sheet.

The company also continues to delay its Neutron rocket program, a large reusable launch vehicle that is widely considered critical to the company’s long-term competitive positioning.

A further delay to the Neutron program could weigh heavily on the stock, given how much of the current valuation appears to be tied to that vehicle’s future revenue potential.

The bull case for Rocket Lab is not without merit, as the combination of a record backlog and a rapidly expanding space economy gives the company a credible growth narrative.

However, the gap between that narrative and the current share price may represent the central risk facing investors who are considering buying in at today’s levels.

For those who got in early, the returns have been exceptional, but the next five years will likely be defined by whether Rocket Lab can execute on Neutron and close the gap between its valuation and its fundamentals.