Arista Networks makes the switches and software that move data around inside large computer networks. When a cloud company or AI lab needs thousands of machines to talk to each other at enormous speed, they buy Arista's hardware and its operating system, called EOS, to run the whole network. Arista gets paid each time a customer orders new switches or routing gear, and then earns additional recurring money through support contracts that customers renew year after year. In 2025, about 84% of total revenue came from products and 16% from services, with the two largest customers alone accounting for 26% and 16% of all revenue respectively. The diagram below traces where the money goes.

Five years of financial data tell a consistent story: Arista has grown fast and stayed profitable while building a large cash cushion. Revenue has grown every single year, from $2.9 billion in 2021 to $9.0 billion in 2025. That is more than three times the starting level in just four years. What makes this more than a simple growth story is that gross margin, meaning the share of each dollar left after paying for the hardware and support, has held steady throughout. It dipped slightly in 2022, recovered, and then stabilised at around 64% in both 2024 and 2025.

Cash generation is what gives the revenue growth its weight. Free cash flow, meaning the cash left after spending on the business, rose from $1.0 billion in 2021 to $4.3 billion in 2025. The company carries no net debt. Instead, it held $10.7 billion in cash, equivalents, and marketable securities at the end of 2025. That pile is not sitting idle: Arista spent $1.6 billion repurchasing its own shares during 2025 and paid $300 million to acquire the VeloCloud SD-WAN portfolio from Broadcom, adding software-defined networking for branch offices to its product range.

The engine behind these numbers is demand from a small group of very large customers. Cloud and AI giants, the kind of companies building enormous data centers for artificial intelligence work, accounted for roughly 48% of Arista's revenue in 2025. That concentration is what drives the growth, but it is also the source of the most serious risks.

Arista's own filings are direct about this: the two largest customers have shown unpredictable ordering patterns, and when they shift capital spending priorities toward or away from AI infrastructure, Arista feels it immediately. The company has also seen more customers running product trials with formal acceptance periods before officially booking revenue, which makes quarterly numbers harder to predict.

Beyond customer concentration, three other risks stand out from the company's disclosures. First, Arista relies almost entirely on a single chip supplier, Broadcom, for the switching chips inside its products. There is no written guarantee of supply, and no alternative is waiting in the wings. Second, manufacturing happens in Malaysia, Vietnam, and Mexico, with components from China and Taiwan. New US tariffs introduced since 2025 could raise production costs in ways that are difficult to pass on to customers, squeezing the margins that have held so steady. Third, the AI networking boom that is driving demand may not last. Customers could overestimate how much networking gear they need, cancel orders with little notice, or find ways to reduce their spending.

Research and development spending rose to $1.24 billion in 2025, up 24% from the year before. Arista is racing to build out its Etherlink family of 800G switches, which are designed to handle the enormous data flows that AI training clusters demand. The bet on Ethernet as the standard for AI networking, rather than competing technologies like InfiniBand or NVLink from Nvidia, is central to that spending.

The competitive landscape is tightening. Cisco remains the dominant force in data center networking. Hewlett Packard Enterprise acquired Juniper Networks in 2025, creating a larger rival. Nvidia bundles its own networking products with its graphics chips, making it harder for Arista to win deals inside AI clusters where Nvidia hardware is dominant. White-box networking, where companies buy generic hardware and run open-source software on it, continues to offer a lower-cost alternative for some buyers.