Tectonic Therapeutic, Inc. (TECX) stock intrinsic value fair value estimate & owner earnings analysis

Tectonic Therapeutic is a clinical-stage biotechnology company with no products for sale and no revenue. It became the public company it is today through its 2024 merger with AVROBIO, so the earlier financial history under this listing belongs to a different business and is not used here. The company is developing two lead drug candidates. TX45 is an engineered form of the hormone relaxin (an Fc-relaxin fusion molecule), being tested in a Phase 2 trial called APEX in patients with pulmonary hypertension caused by heart failure with preserved ejection fraction. Topline APEX results are expected in 2026. TX2100 is an antibody aimed at hereditary hemorrhagic telangiectasia, a condition that causes severe bleeding. Its Phase 1a trial in healthy volunteers randomized its first subject in February 2026, with topline results expected in the fourth quarter of 2026. What the business earns: nothing. Cash used in operations was $60.1 million in 2025 and $59.1 million in 2024. Stock-based pay of $10.5 million in 2025 and $3.5 million in 2024 is treated as a real cost, and the small equipment spending ($208,000 in 2025) is deducted in full because there is no revenue growth to justify it. On that basis, owner earnings were negative $70.7 million in 2025 (about negative $3.86 per share) and negative $52.4 million in 2024 (about negative $6.18 per share; the 2024 share count is a weighted average that reflects the merger's share conversion). An independent rebuild from net loss, depreciation, stock pay and other non-cash items matched the cash-flow result exactly in both years. Because the company earns no owner earnings, the value we can defend is its cash. Cash was $227.1 million at June 30, 2026, after $253.8 million at year-end 2025, when the company had total liabilities of only $9.7 million and no borrowings beyond a small lease obligation. In 2025 it raised about $173 million net through a private placement of 3.69 million shares. Cash used in operations over the first half of 2026 was $39.9 million, roughly $80 million a year. Diluted shares were about 18.96 million in the second quarter of 2026. Cash fell by less than the operating cash used in the first half, which suggests some cash came in from financing, but we could not itemize it from the data available; we do not count on any future inflows. Base case, $9.87 per share. The company keeps spending at its first-half pace until the APEX and TX2100 results arrive at the end of 2026, leaving about $187.2 million of cash, or $9.87 per share. We credit nothing for either drug. Part A of the completed open-label Phase 1b trial (19 patients with this condition) showed TX45 was well tolerated with no serious or severe adverse events and lowered pulmonary capillary wedge pressure, a pressure measure linked to exercise capacity and outcomes, by 19.0% across the study population, but a small early study does not tell us how likely a Phase 2 success or an approval is, and we do not invent one. Without a named, evidenced source of future earnings, the drugs are worth $0 in this case. Bear case, $5.67 per share. The results do not lead to a sale or partnership, and the company keeps funding the pipeline anyway. It has said it plans to start a TX2100 Phase 2 trial in early 2027. Spending continues at the current pace through the end of 2027, using about $119.6 million and leaving $107.5 million, or $5.67 per share. This is the cash-erosion risk that comes with a business that spends about $80 million a year and earns nothing. Bull case, $9.87 per share. We could not name and evidence any upside beyond the cash itself, so the bull case equals the base case. A positive APEX result would clearly matter, but we cannot say what it would be worth without a probability or a contract, and neither exists today. The drugs therefore represent an unpriced option rather than a value we can measure. What would make this wrong: cash burn rising above the current pace, for example from larger late-stage trials, would lower all three cases; new share sales would dilute existing holders; and a successful trial that leads to a partnership or approval would make the true value higher than we show, since none of that is included. Margin-of-safety price: $5.00 per share, below the bear case, reflecting the cash-burn risk and assigning no value to drug success. Price alone is sufficient.