Cambridge biotech tracker · Waltham
Sionna Therapeutics
Listed on Nasdaq as SION, filed under SEC industry code 2834 (pharmaceutical preparations). Fiscal year ends in December. Numbers below are from the company’s own SEC filings through Q2 '26.
- Cash & investments
- $268M
- Q2 '26 · Jun 30, 2026
- Burn per quarter
- $19.0M
- avg. operating cash flow, 4 qtrs
- Runway
- 3.5 yrs
- 3+ years
- Net loss
- $29.9M
- Q2 '26
- R&D expense
- $21.9M
- 67% of opex
- Raised, last 4 qtrs
- +$6.3M
- net financing cash flow
Cash & investments
Quarter-end balance
Operating cash flow
Per quarter; below zero is burn
R&D expense
Per quarter
Two views of the runway
Compare across the clusterThe outside view
3.5 years
Cash at Q2 '26 divided by the average burn of the last four quarters, $6.3M a month.
Management’s own date
Into 2028
Jan–Dec 2028
That implies $8.9M to $14.8M a month, 1.4–2.3× the recent pace.
Planning to spend faster“Based upon our current operating plans, we believe that our existing cash, cash equivalents and marketable securities will be sufficient to fund our operations into 2028.”
Pipeline
No active company-sponsored trials.
| Study | Phase | Status | Enrolled | Primary completion |
|---|---|---|---|---|
| Proof-of-concept Study to Evaluate the Safety, Tolerability, Pharmacodynamics, and Pharmacokinetics of SION-719 When Added to TrikaftaNCT07108153 · Cystic Fibrosis (CF)Phase 2Jun 2026 | Phase 2 | Completed | ||
| Safety, Tolerability, and Pharmacokinetics of Multiple Dose Combinations of SION-451 and Complementary Modulators SION-2222 and SION-109 in Healthy Participants.NCT07035990 · Cystic Fibrosis (CF)Phase 1Mar 2026 | Phase 1 | Completed |
Interventional studies where this company is the lead sponsor, from ClinicalTrials.gov. Primary completion is when the last patient is measured on the primary endpoint, which is when the data exists rather than when it is announced. Extension, rollover and healthy-volunteer studies are listed but marked as non-catalysts, because they finish long after the result that mattered. Sponsors revise these dates as enrollment moves, so an estimate is a plan rather than a promise.
The controller’s read
What the filings say.
Generated from the numbers above using the same questions I ask when I open a client’s books: how long the cash lasts, what is driving the gap between loss and burn, and where the accounting judgment sits.
Get this read on your companyAbout 3.5 years of runway
Cash and investments of $268M at Q2 '26 against an average operating cash burn of $19.0M per quarter over the last four reported quarters runs out around December 2029. More than two years of runway means the finance conversation is about deployment, not survival.
Cash position up $233M since Q3 '24
Net financing inflows of $6.3M over the last four quarters, from equity, debt, or ATM sales, more than covered operating burn. The balance is the number the board watches; the trend is the number the auditors watch.
Net loss runs $7.7M above cash burn
The Q2 '26 net loss of $29.9M includes non-cash charges, including $6.8M of stock-based compensation, that do not consume cash. Burn, not net loss, is what runway is built on.
R&D is 67% of operating expenses
$21.9M of R&D against $32.5M of total operating expenses in Q2 '26, with G&A at $10.6M. For a clinical-stage company, the accounting questions live inside that R&D line: CRO and CMC accruals, milestone recognition, and what gets capitalized versus expensed under ASC 730.
Accumulated deficit of $313M
Total losses since inception. It is also roughly the size of the net operating loss carryforward the tax provision has to track, subject to Section 382 limits after each ownership change.
Quarterly detail, eight quarters
| Quarter | Cash & inv. | Op. cash flow | Net income | R&D | G&A | Revenue | Stock comp | Financing |
|---|---|---|---|---|---|---|---|---|
| Q3 '24 · Sep 30, 24 | $35.7M | −$17.7M | −$25.4M | $24.6M | $3.4M | — | $1.0M | −$996K |
| Q4 '24 · Dec 31, 24 | $168M | −$11.8M | −$15.8M | $14.3M | $3.9M | — | $1.1M | −$1.4M |
| Q1 '25 · Mar 31, 25 | $355M | −$16.3M | −$16.5M | $13.7M | $6.0M | — | $2.1M | $202M |
| Q2 '25 · Jun 30, 25 | $337M | −$18.2M | −$18.1M | $15.4M | $6.5M | — | $2.8M | −$312K |
| Q3 '25 · Sep 30, 25 | $325M | −$15.2M | −$20.3M | $16.0M | $7.8M | — | $3.3M | $2.0M |
| Q4 '25 · Dec 31, 25 | $310M | −$16.6M | −$20.4M | $15.2M | $8.4M | — | $3.8M | $1.7M |
| Q1 '26 · Mar 31, 26 | $290M | −$21.8M | −$26.8M | $19.0M | $10.6M | — | $6.6M | $1.9M |
| Q2 '26 · Jun 30, 26 | $268M | −$22.2M | −$29.9M | $21.9M | $10.6M | — | $6.8M | $749K |
Source: SEC EDGAR XBRL company facts, latest filed value for each period. Fourth quarters are derived from annual less nine-month figures; quarterly cash flows are derived from year-to-date amounts. Not investment advice. If a figure disagrees with the filing, the filing is right.