SI-BONE, Inc. (SIBN) stock intrinsic value fair value estimate & owner earnings analysis

SI-BONE makes implants (iFuse, iFuse-3D, iFuse TORQ, iFuse Bedrock Granite) for fusing the sacroiliac joint and pelvis. Revenue has grown from $67 million in 2019 to $201 million in 2025 (about 20% a year) with a gross margin near 80%. The business is not yet profitable on the measure we use, owner earnings (operating cash flow, less inventory and receivable build, less stock compensation, less the part of capital spending needed just to stand still). That figure was about -$1.45 per share in 2020, -$1.91 in 2022, -$0.89 in 2024 and -$0.43 in 2025, so the loss has narrowed for three straight years. Operating cash flow was roughly break-even in 2025 (-$0.7 million), but that is flattered by adding back $25.5 million of stock compensation, which we treat as a real cost, and by inventory and receivable growth of about $14 million that we strip out to avoid timing swings. Base case (about $5 per share): We credit only the improvement already visible in the filings: stock compensation has stayed flat near $25 million for three years while revenue grew about $30 million a year at a roughly 79-80% gross margin, so owner earnings per share moved from -$1.14 (2023) to -$0.89 to -$0.43. We assume the 2026 figure is still slightly negative (about -$0.20, versus a trailing improvement of about $0.46), reaching break-even in 2027 and roughly $0.90 per share by 2030, held flat to 2035 and then fading over about five years as the current product family ages. We left out further revenue growth, new products and international expansion, because they have not yet been shown to be self-funded. Bear case (about $0): Revenue growth slows while spending on surgeons, training and stock compensation stays where it is, so owner earnings stay negative. Because the company has little debt, we do not see it owing more than it is worth, but nothing evidenced then supports a positive value, and continued losses would also dilute existing holders. Bull case (about $14): The company's own operating leverage continues at the pace of the past three years. Owner earnings reach break-even in 2027 and approach $3 per share by 2035, with earnings persisting for about five more years. This requires revenue to keep compounding near its 20% record while costs grow much slower. What would make this wrong: gross margin (79.6% in 2025, up from 79.0%) is high, so the main risk is spending, not product cost. If growth needs stepped-up spending, or stock compensation rises, the improvement stalls. Our earnings history also uses estimated working-capital lines; a small reconciliation gap to net income plus non-cash charges (other non-cash items not separately pulled) could not be fully closed from the structured data. Valuations for a company still losing money are wide; the margin-of-safety price reflects a large margin of safety.