Read the risk factors like a thriller, because that is where the real numbers hide. Rocket Lab's 2021 Form 10-K, its first annual report after the 2021 SPAC combination, discloses that its top five backlog customers accounted for approximately 47% of backlog as of December 31, 2021. Nearly half the contracted runway sat with five customers — and the filing flags that those customers 'could experience' problems that flow straight into Rocket Lab's results.
For a capital-markets desk, concentration at a newly public space company is the number that governs how durable the backlog really is. Backlog is the company's forward-revenue story; a 47% top-five share means the story is only as resilient as a handful of contracts. If one large customer slips a launch, cancels, or hits its own funding wall, the dent lands on a small revenue base.
The fairer read is that early-stage launch and space-systems businesses are concentrated by nature — the customer universe for orbital launch and satellite buses is small, and large anchor contracts are how a young company builds backlog at all. Concentration here is partly a sign of having won meaningful customers. But it is still risk, and the filing rightly treats it as such.
The forward question entering 2022: whether Rocket Lab broadens its backlog base as it scales Electron cadence and builds toward its space-systems business. Track whether the top-five share falls in later filings. Filing on sec.gov; index via EdgarBeast.