Fastly (FSLY) Q4 2025 earnings review
A Validated Turnaround: Acceleration Across the Board
Fastly delivered a definitive 'inflection point' quarter. Revenue growth accelerated to 23% YoY (up from 15% in Q3), beating the high end of guidance. More importantly, the forward-looking RPO metric exploded 55% YoY, signaling that the go-to-market overhaul is locking in long-term commitments. Operational rigour also materialized: Non-GAAP Gross Margins expanded 650bps to 64%, and the company swung from a loss to a record $21.2M Non-GAAP operating profit. Fastly is no longer just promising a turnaround; they are printing the receipts.
🐂 Bull Case
RPO (Remaining Performance Obligations) surged 55% YoY to $354M. This significantly outpaced revenue growth, indicating that customers are signing larger, longer-term contracts. This builds a defensive moat and high visibility for FY26.
The platform consolidation thesis is working. Security revenue grew 32% YoY to $35.4M, outpacing the core network business. 34% of revenue now comes from top 10 customers, who are increasingly adopting the full security suite.
🐻 Bear Case
Despite strong non-GAAP profits, the company posted a GAAP Net Loss of $15.5M. Stock-Based Compensation (SBC) remains high at $32.3M (19% of revenue), which continues to dilute real shareholder returns.
Revenue concentration in the Top 10 customers increased slightly to 34% (from 32% in Q3). While growth is good, increased dependency on a few large giants (like the undisclosed TikTok/ByteDance exposure) remains a structural risk.
⚖️ Verdict: 🟢🟢
Bullish. Fastly checked every box: accelerated top-line growth, massive backlog accumulation (RPO), and significant margin expansion. The guidance suggests this momentum carries into 2026.
Key Themes
Security Cross-Sell Ignition
Accelerating. Security revenue accelerated to 32% YoY growth, up from 30% in Q3 and 15% in Q2. It now represents over 20% of total revenue. The 'platform' sale is working—customers are not just buying delivery; they are buying the WAF, Bot Management, and API security stack. This mix shift is accretive to gross margins.
RPO Explosion
Accelerating. RPO growth of 55% YoY is the standout metric of the quarter. In absolute terms, RPO jumped from $268M in Q3 to $354M in Q4. This indicates that the new Go-To-Market leadership is successfully locking in multi-year commitments rather than relying on month-to-month traffic volatility.
Operational Leverage
Accelerating. The company demonstrated it can grow efficiently. Non-GAAP Operating Income swung from a loss of $2.8M a year ago to a profit of $21.2M. This $24M swing was driven by Gross Margin expansion (to 64%) and disciplined OpEx management, proving the business model scales.
Stock-Based Compensation (SBC)
Stable (High). SBC remains a significant weight on GAAP profitability. In Q4, SBC was $32.3M, increasing from $24.9M in the prior year. While the company is generating Non-GAAP profit and Free Cash Flow, the GAAP Net Loss of $15.5M is almost entirely due to SBC. Investors should watch if this line item grows in line with revenue or begins to leverage.
AI as a Network Tailwind
New. Management cited AI as an increasing tailwind for 2026. The launch of 'AI Assistant' (beta) and the 'AI Accelerator' indicates Fastly is positioning its edge network to be the serving layer for AI inference and caching, though revenue contribution is currently small ($6.4M in 'Other' segment, growing 78% YoY).
Other KPIs
Accelerating. NRR improved significantly from 106% in Q3 and 100% in Q1. This proves that the 'land and expand' strategy is working, with existing customers increasing spend by 10% YoY.
Reversing. A massive turnaround from -$7.9M burn in the prior year period. Full year FCF finished at positive $45.8M, validating the company's self-funding capability.
Stable. Added 1 net new enterprise customer sequentially (from 627 in Q3), but up 32 YoY. The growth story is currently driven more by expanding wallet share with existing giants (NRR 110%) than rapid logo acquisition.
Guidance
Accelerating. The midpoint ($171M) implies ~18.5% YoY growth, a significant acceleration compared to the 8% growth seen in 25Q1. Sequentially, it is flat/down slightly from Q4, which is typical seasonality.
Stable. The midpoint ($710M) implies ~14% YoY growth for the full year. While lower than the Q4 exit velocity of 23%, management is likely baking in conservatism regarding usage-based volatility.
Accelerating. Implies more than doubling FY25's result of $22.4M. This confirms the margin expansion story is durable and 2026 will be a year of harvesting profits.
Key Questions
RPO vs Revenue Lag
RPO grew 55% while revenue grew 23%. What is the average duration of these new contracts, and how long until this backlog fully converts to recognized revenue?
Top 10 Concentration Volatility
Top 10 customer concentration ticked back up to 34%. Is this driven by a specific hyperscaler or AI customer, and does this re-introduce churn risk if a single contract is lost?
Gross Margin Ceiling
Gross margins hit 64%, a multi-year high. Is this the new baseline, or were there one-time benefits (like peering settlements or mix shift) that might normalize in Q1?