AC Immune ($ACIU) Stock Hub 2026: First NLRP3 Data, VacSYn Readout Ahead and Funding Into Q4 2027

01 Executive Summary

AC Immune SA is a clinical-stage biopharmaceutical company based at the EPFL Innovation Park in Lausanne, Switzerland, listed on Nasdaq since 2016 and reporting in Swiss francs under international accounting standards. It designs active immunotherapies, which are vaccines that train a patient’s own immune system to produce antibodies against a misfolded protein, and small molecules aimed at the same targets. The proteins in question are alpha-synuclein in Parkinson’s disease, amyloid beta and phosphorylated Tau in Alzheimer’s disease, TDP-43 in amyotrophic lateral sclerosis, and the NLRP3 inflammasome, which sits upstream of neuroinflammation in several of these diseases.

The business combines wholly owned candidates, including ACI-7104, ACI-19764 and ACI-19626, with Alzheimer’s programs partnered with Takeda, Lilly and Janssen. Partner payments provide non-dilutive funding, but both owned and partnered programs carry clinical and commercial uncertainty. Contract revenue is not product sales.

On August 11, 2026 the U.S. Food and Drug Administration granted Fast Track designation to ACI-7104 for early-stage Parkinson’s disease and cleared the company’s Investigational New Drug application. The two decisions arrived together and do different things. The IND clearance is the operative one: it allows the ongoing Phase 2 VacSYn trial, which today runs at twelve sites across Germany, Spain and the United Kingdom, to open sites in the United States. Fast Track is a process designation that permits more frequent written and oral communication with the agency and makes a submission eligible for rolling review and, if the criteria are met at the time, for accelerated approval or priority review. Neither decision is evidence that the drug works, and neither shortens the trial.

The financial position is a small one, held together by partner payments. Total cash resources were CHF 75.4 million at June 30, 2026, about $93.0 million at the August 11 exchange rate, composed of CHF 27.8 million of cash and cash equivalents and CHF 47.6 million of short-term financial assets. That compares with CHF 91.4 million at December 31, 2025. The company states that the position funds operations into the fourth quarter of 2027 and that the statement excludes any further milestone payments. Revenue for the first half of 2026 was CHF 16.2 million against CHF 2.3 million a year earlier, entirely from partner arrangements: CHF 11.0 million recognised on the amended Lilly agreement and CHF 5.2 million on the Takeda arrangements. Research and development expense fell to CHF 22.2 million from CHF 32.7 million, which the company attributes to the pipeline focus programme announced in the third quarter of 2025 and to non-recurring manufacturing costs in the prior period, partly offset by CHF 1.9 million of new spending as the NLRP3 inhibitor entered Phase 1. The net loss narrowed to CHF 12.9 million from CHF 40.2 million, and the loss per share to CHF 0.13 from CHF 0.40.

The balance sheet carries one line that deserves attention before any judgement about equity. Total liabilities of CHF 115.2 million include CHF 89.5 million of short-term deferred contract revenue and CHF 0.8 million of long-term deferred contract revenue. That deferred revenue is the unrecognised remainder of partner payments already received, principally the $100.0 million Takeda upfront of May 2024, and it will be released into revenue as the underlying work is performed rather than being repaid in cash under normal circumstances. Shareholders’ equity of CHF 35.2 million therefore understates the funded position, while the accumulated deficit of CHF 450.4 million records what it has cost to get here.

02 What The August 11 Decision Does And Does Not Do

The announcement of August 11, 2026 contains two separate regulatory acts that are easy to conflate. Reading them apart is the difference between understanding the news and repeating a headline.

IND clearance

The August 11 IND clearance allows the planned expansion of VacSYn to US sites. It does not establish that those sites have opened or enrolled patients. The registry record retrieved September 5 was last updated in November 2025 and lists European sites; it therefore predates this regulatory announcement.

Fast Track designation

Fast Track is granted to programmes intended to treat a serious condition where non-clinical or clinical data demonstrate the potential to address an unmet medical need. What it confers is process: more frequent meetings and written communication with the review division, eligibility for rolling review of a marketing application, and eligibility to be considered for accelerated approval and priority review if the relevant criteria are met at the time of submission. What it does not confer is any conclusion about efficacy, any reduction in the evidentiary standard, or any acceleration of the trial itself. Designations are also revocable if a programme no longer meets the criteria.

The company’s own framing is consistent with that reading. The release states that the designation “reflects the early interim Phase 2 data demonstrating safety, tolerability and immunogenicity, and providing first signals that targeting underlying a-syn pathology with an active immunotherapy could potentially impact PD”. The word doing the work in that sentence is “signals”. Interim results reported at 76 weeks met their immunogenicity targets with a 100% responder rate and showed no clinically relevant safety issues; the efficacy language throughout has been about trends and stabilisation, not about a met endpoint.

Why the sequence matters

The two regulatory steps were announced together. Neither establishes an agreed registrational design or a specific readout date. The latest company guidance is H2 2026 for full Part 1 week-100 results; August 11 falls inside that window, not four weeks before it.

03 What The Company Actually Is Today

AC Immune has no approved product, no product revenue and no commercial organisation. Its entire income statement is partner money: upfront payments, milestones and research funding recognised over the periods in which the associated work is performed. That makes the revenue line lumpy in a way that a reader used to commercial companies can misread. Revenue rose from CHF 2.3 million to CHF 16.2 million between the first halves of 2025 and 2026, an increase of more than six times, and none of it reflects demand for anything.

Two technology platforms sit underneath the pipeline. SupraAntigen is the active immunotherapy platform: short peptide antigens presented in a way designed to raise antibodies against a specific conformation of a misfolded protein while avoiding a T-cell response against the normal form. Morphomer is the small-molecule platform: brain-penetrant compounds designed to bind pathological protein aggregates inside the cell, where an antibody cannot reach. The distinction matters because the two platforms address the same targets from opposite sides of the cell membrane, and the company has partnered the Alzheimer’s applications of both while keeping the Parkinson’s applications.

The three wholly owned clinical programmes

ACI-7104 is the anti-alpha-synuclein active immunotherapy in Phase 2 for early Parkinson’s disease, and it is the reason most people look at this company. The optimised formulation carries the fuller designation ACI-7104.056 in trial documents; the August 2026 releases use the shorter ACI-7104 for the same candidate.

ACI-19764 is the wholly owned NLRP3 inhibitor. Its preliminary readout has occurred; see the updated development section below for the remaining milestones.

ACI-19626 is a first-in-class positron emission tomography tracer for TDP-43, the protein that aggregates in the great majority of amyotrophic lateral sclerosis cases and in a substantial share of frontotemporal dementia. Preliminary Phase 1 results presented in 2026 showed increased uptake in the brains of patients with ALS. A tracer is not a therapy, but a validated TDP-43 imaging agent would be the first way to see that pathology in a living patient, which is a prerequisite for running efficient trials in those diseases.

An earlier-stage small-molecule programme against intracellular alpha-synuclein is described as advancing towards the clinic, with a lead declaration guided to the second half of 2026.

Why the shape of the company changed in 2025

The pipeline focus initiative announced in the third quarter of 2025 is visible in the numbers rather than described in them. Research and development expense fell by CHF 10.5 million year on year in the first half, of which the company attributes approximately CHF 4.9 million to lower personnel and operational spend as a direct result of that initiative and CHF 5.8 million to lower clinical programme spend, including active immunotherapy manufacturing costs that did not recur. General and administrative expense fell from CHF 8.3 million to CHF 7.7 million for the same reason. A company that cuts its research spending by a third while its lead asset approaches a decisive readout is making a deliberate choice about where its remaining francs go.

04 VacSYn: The Trial That Defines The Company

VacSYn is registered as NCT06015841. The record retrieved September 5, 2026 was last updated November 21, 2025: active, not recruiting; actual start July 24, 2023; estimated primary and study completion January 2028. These whole-study dates do not replace management’s H2 2026 guidance for Part 1 results.

The design, as registered

The structure is a screening period of up to eight weeks, a 74-week double-blind treatment period and a 26-week post-treatment follow-up, which is where the week-100 endpoint timing comes from. Up to three cohorts of sixteen patients each are foreseen, randomised three to one between ACI-7104.056 and placebo, with the second and third cohorts optional; one cohort may be expanded to bring the total study population to as many as 150 patients, and in an expanded cohort the randomisation shifts to two to one. Treatment is given by intramuscular injection.

Eligibility is narrow, which is deliberate in a disease-modification study and consequential for how the results should be read. Patients must have clinically established early Parkinson’s disease under the modified Movement Disorder Society criteria with motor symptoms present for no more than two years at screening, be aged between 40 and 75, be at modified Hoehn and Yahr stage I or II, and be on levodopa monotherapy at 300 mg per day, stable for three months before baseline. A screening DaT-SPECT scan read centrally must be consistent with Parkinson’s disease. Known carriers of PRKN, PINK1, DJ1 and LRRK2 mutations are excluded, as are patients with a history of freezing episodes or falls, and patients who have used dopamine agonists, MAO-B inhibitors, COMT inhibitors, amantadine or anticholinergics for more than ninety days in total or within ninety days of baseline.

The endpoints

The primary endpoints are safety and immunogenicity, not efficacy: adverse events by intensity and causality from screening to week 100, abnormal MRI results, clinically significant changes on physical and neurological examination to week 74, suicidal ideation or behaviour on the Columbia scale, and the level of alpha-synuclein-specific antibodies in serum generated by the vaccine. The secondary endpoints are the ones an investor watches: alpha-synuclein-related biofluid biomarkers, dopamine transporter levels in specific brain regions measured by DaT-SPECT imaging, and change from baseline in Part III of the Movement Disorder Society Unified Parkinson’s Disease Rating Scale, all to week 100. Change in motor and non-motor function on the full MDS-UPDRS is listed as an other outcome.

That hierarchy is the single most important structural fact about this readout. A Phase 2 study whose primary endpoints are safety and antibody titres can succeed on its own terms while telling the market very little about whether patients do better, and it can equally show a promising clinical trend that is not statistically powered to mean anything. Both outcomes are possible in the same data set, and the company has been consistent in describing the clinical measures as trends.

Where it runs

The November 2025 registry version lists twelve sites in Germany, Spain and the United Kingdom. Its lack of US sites cannot establish the current operational position after the August 2026 IND clearance. US expansion is announced; actual site activation needs a subsequent update.

05 The December 2025 Interim Data, Read Precisely

The interim analysis reported on December 11, 2025 is the evidentiary base for everything that has happened since, including the Fast Track grant. It covered Part 1, which randomised 34 patients three to one. All participants in the analysis had been treated for at least twelve months, and twenty of them for up to eighteen months, which is the 74-week mark.

Immunogenicity, where the result is unambiguous

All target criteria were met. The responder rate was 100%. At week 76, two weeks after the sixth immunisation, antibody titres in serum were more than 500-fold higher than in the placebo group, and antibody responses to both the immunising peptide and the native alpha-synuclein peptide were boosted after each dose from the second immunisation onward, while the placebo group showed no detectable signal. Titres in cerebrospinal fluid rose with successive immunisations and average IgG levels in CSF were also more than 500-fold higher than placebo, which is the evidence that the antibodies cross the blood-brain barrier. Changes from baseline in CSF antibody concentration correlated with changes in serum titres, with a Spearman coefficient of 0.92 at week 24 and 0.85 at week 76, both at p below 0.05.

Biomarkers, where the result is directional

Total alpha-synuclein in cerebrospinal fluid stabilised in the treatment arm while declining in the placebo arm, with a post-hoc p value of 0.018. The company’s explanation is that antibody binding stabilises the target or increases clearance from the brain, whereas untreated progression sees alpha-synuclein accumulate in tissue and fall in CSF. Neurofilament light chain, a general marker of neuronal damage, remained stable in the treatment arm and rose in the placebo arm. Plasma glial fibrillary acidic protein and DaT-SPECT imaging were described as suggesting stabilised pathology, without figures attached.

Two qualifications belong next to those results rather than in a footnote. The alpha-synuclein CSF result is explicitly post-hoc, meaning the analysis was defined after the data were seen, which lowers its evidentiary weight regardless of the p value. And the comparison group is small: in a three-to-one randomisation of 34 patients, the placebo arm holds roughly eight or nine people, so a placebo trajectory that looks like textbook progression can also be the arithmetic of a handful of patients.

Clinical measures, where the result is a trend

At week 74 the treated group showed no meaningful progression in mean total score or change from baseline on Part III of the MDS-UPDRS, while the placebo arm increased as expected in normal disease progression. Stratifying by levodopa on and off state, the difference between the arms was described as further enhanced. The company’s own word for this is “suggestive of a trend for stabilization”, and Professor Werner Poewe, quoted in the release as an outside expert, described the consistency of the trends as promising and the findings as fully supporting further development, language that stops well short of a claim of efficacy.

Safety

No clinically relevant or serious adverse events considered related to the study drug had been reported at weeks 50 and 76. The most common adverse events were transient injection-site reactions in 56% of patients, headache in 15% and fatigue in 12%. For an active immunotherapy, that profile is the point: the historical fear with alpha-synuclein vaccines is an autoimmune reaction against the normal protein, and nothing of that kind has appeared.

Why the field is watching this particular mechanism

Active immunisation aims to generate the patient’s own antibody response; passive immunotherapy administers antibodies directly. Differences in exposure and dosing do not establish superiority. VacSYn’s small interim analysis cannot determine whether this approach improves clinical outcomes or outperforms another program.

06 The Rest Of The Owned Pipeline

ACI-19764, the NLRP3 inflammasome inhibitor

The NLRP3 inflammasome is a protein complex inside immune cells that, when activated, drives the release of interleukin-1 beta and a broader inflammatory cascade. In the brain, chronic activation of that pathway in microglia is one of the mechanisms by which protein aggregation is thought to become neuronal damage. Inhibiting it is an approach with a wide potential application and a long history of disappointment, and several large companies have programmes in the area.

The August 20 preliminary analysis reported tolerability and CSF exposure, without serious adverse events or treatment withdrawals to date. Cardiovascular-risk cohort dosing had begun. Initial results were guided before year-end on August 20; the September 2 invitation says around year-end; full Phase 1/1b results in H1 2027. This does not establish neurological efficacy. Company release filed with SEC.

The programme is the reason research spending rose CHF 1.9 million in the first half even as the total fell, and it is the second of the two near-term catalysts management named.

ACI-19626, the TDP-43 PET tracer

TDP-43 aggregation is present in the overwhelming majority of amyotrophic lateral sclerosis cases and in a large share of frontotemporal dementia, and it is also found alongside Alzheimer’s pathology in many older brains. Unlike amyloid and Tau, it cannot currently be imaged in a living patient, which means trials in those diseases enrol on clinical grounds and cannot confirm the target is present. A first-in-class tracer would change that.

Preliminary Phase 1 results showed increased uptake in the brains of patients with ALS. That is an early and encouraging result rather than a validated tracer; the standard for imaging agents is demanding, and the path from a signal to a diagnostic used in trials is long. The commercial logic, if it works, is a partnership with an imaging company rather than a company-built business, which is how AC Immune has handled diagnostics before.

The intracellular alpha-synuclein small molecule

An early-stage Morphomer programme targeting alpha-synuclein inside the cell is advancing towards the clinic, with a lead declaration guided to the second half of 2026. Conceptually it is the complement to ACI-7104: antibodies raised by a vaccine act on extracellular and membrane-associated species, while a small molecule can reach aggregates inside the neuron. A company that owned both would have two shots at the same biology, which is a stronger strategic position than one.

07 The Partnered Programmes And What They Are Worth

Three partners fund the Alzheimer’s side of the pipeline. Their money is the reason the company can run a Parkinson’s programme it owns outright, and the terms are worth stating with their limits attached, because contingent milestone ceilings are the most frequently misquoted numbers in biotechnology.

Takeda and ACI-24

In May 2024 AC Immune signed a worldwide option and licence agreement with Takeda covering active immunotherapies targeting amyloid beta, including ACI-24.060. AC Immune received a $100.0 million upfront payment, recorded at CHF 92.3 million, and is eligible for an option exercise fee described as being in the low-to-mid nine-figure dollar range plus additional development, commercial and sales-based milestones of up to approximately $2.1 billion, equivalent to CHF 1.7 billion, if every milestone is achieved over the life of the agreement. Royalties are tiered in mid-to-high teens percentages of worldwide net sales. Takeda may terminate the agreement at any time on ninety days’ notice, a clause that belongs in any assessment of how firm this funding is.

The clinical vehicle is the Phase 1b/2 ABATE trial in prodromal Alzheimer’s disease. In February 2026 the agreement was amended to initiate a final cohort, AD4, which evaluates ACI-24 with an additional adjuvant intended to boost immunogenicity. First patients in that cohort were dosed on April 30, 2026, triggering a $12.0 million milestone payment recognised at CHF 9.5 million at the transaction date. On June 30, 2026 the company reported twelve-month interim data from the first three cohorts, covering 74 prodromal Alzheimer’s patients: generally safe and well tolerated, no evidence of amyloid-related imaging abnormalities with oedema, and anti-amyloid antibody responses detected at every dose level. The absence of ARIA-E is the differentiating claim for an active immunotherapy against a background of approved anti-amyloid antibodies where that complication is a labelled risk.

Eli Lilly and the Tau Morphomer programme

The licence and collaboration agreement dated December 11, 2018 was amended in April 2026 to extend research into new lead Tau Morphomer candidates and potential back-up compounds. AC Immune received a CHF 10.0 million upfront payment and a further CHF 1.0 million milestone in the first half of 2026 on delivery of a preclinical data package, and a subsequent milestone is tied to Phase 1 dosing. Remaining development, regulatory and commercial milestones are disclosed as over CHF 1.7 billion with tiered royalties in the low double digits. Those two payments are the CHF 11.0 million that dominates the half-year revenue line.

Johnson & Johnson’s Janssen unit and ACI-35

The phospho-Tau active immunotherapy ACI-35.030 is partnered with Janssen. The company continues to list the collaboration among its partnered Alzheimer’s programmes in the corporate description accompanying its August 2026 releases, and no new financial terms or clinical milestones for that programme were disclosed in the half-year materials.

How to read the aggregate

The “more than $4.5 billion in potential milestone payments” that appears in every AC Immune release is a sum of maximum contingent amounts across agreements, payable only if candidates are approved and reach specified sales thresholds. It is not a receivable, not a valuation and not a forecast. The number that describes the partnerships in cash terms is what has actually been paid: a $100.0 million Takeda upfront in 2024, a $12.0 million Takeda milestone in April 2026, and CHF 11.0 million from Lilly in the first half of 2026. The unrecognised remainder of those payments sits on the balance sheet as CHF 89.5 million of short-term deferred contract revenue and CHF 0.8 million of long-term deferred contract revenue.

08 Financial Position

AC Immune reports in Swiss francs as a foreign private issuer, with an annual Form 20-F and updates furnished on Form 6-K. The June 30 half-year financial statements were furnished August 5. The company also released a first-quarter financial and corporate update on April 30; the half-year statement format should not be confused with the frequency of all financial updates.

Revenue of CHF 16.2 million against CHF 2.3 million, research and development of CHF 22.2 million against CHF 32.7 million, general and administrative of CHF 7.7 million against CHF 8.3 million, and other operating income of CHF 0.1 million produce total operating expenses of CHF 29.8 million and an operating loss of CHF 13.6 million, against CHF 38.8 million a year earlier. The finance result swung from a CHF 1.5 million loss to a CHF 0.7 million gain, driven by CHF 2.9 million of higher foreign exchange gains partly offset by CHF 0.7 million less interest income on short-term financial assets. There is no income tax charge. The loss for the period is CHF 12.9 million, or CHF 0.13 per share on 101,963,177 weighted average shares.

The runway statement and what it assumes

The company’s own words are that cash resources “are expected to provide sufficient capital to last into Q4 2027, excluding potential milestone payments”. The going-concern note states separately that the company believes it can meet its obligations for at least twelve months from the filing date after considering CHF 27.8 million of cash and CHF 47.6 million of short-term financial assets.

Cash-resource movements include partner receipts, operating spending and other cash flows. The CHF 16.6 million Q1 reduction and broadly stable Q2 position should not be treated as a constant quarterly burn rate. Management’s runway estimate is conditional on its operating assumptions; trial expansion, spending changes or financing can alter it.

The balance sheet lines that get misread

Total assets are CHF 150.4 million, of which CHF 50.4 million is an intangible asset carried unchanged from December 31, 2025, CHF 47.6 million short-term financial assets, CHF 27.8 million cash, CHF 9.9 million accounts receivable that were nil at year end, and CHF 4.4 million of prepaid expenses. Total liabilities are CHF 115.2 million, of which CHF 89.5 million is short-term deferred contract revenue and CHF 0.8 million long-term deferred contract revenue, CHF 9.1 million net employee defined benefit liabilities, CHF 7.1 million accrued expenses, CHF 4.1 million of lease liabilities across current and non-current, and CHF 3.1 million of deferred income. Shareholders’ equity is CHF 35.2 million against CHF 44.9 million at year end, with share premium of CHF 483.6 million and accumulated losses of CHF 450.4 million.

A reader who sees CHF 115.2 million of liabilities against CHF 150.4 million of assets and concludes the company is heavily indebted has misread the largest line. AC Immune has no bank debt, no convertible notes and no term loan. The CHF 89.5 million of short-term deferred contract revenue is partner money already banked and not yet recognised in the income statement, and it converts into revenue as work is performed rather than into a cash outflow. The defined benefit pension liability of CHF 9.1 million is a Swiss employer obligation, real but long-dated. The genuine claims on cash in the next twelve months are the CHF 1.5 million of trade payables, CHF 7.1 million of accrued expenses and CHF 0.8 million of current lease liabilities.

09 Capital Structure And Dilution

The company-declared share count is 101,742,231 shares outstanding at December 31, 2025, stated on the cover of the Form 20-F filed on March 13, 2026. The equivalent figures were 100,410,377 at December 31, 2024 and 99,197,829 at December 31, 2023, so the count has grown by roughly 1.3% a year over two years. For a clinical-stage company with no product revenue, that is a remarkably quiet share register, and it is a direct consequence of the partnering strategy: the Takeda upfront of $100.0 million in May 2024 is money that did not have to be raised from shareholders.

The half-year statements do not restate a point-in-time outstanding count at June 30, 2026. What they do give is the weighted average used for the loss per share, 101,963,177 shares for the six months against 100,519,884 a year earlier, and the treasury position, which fell from 10,899,773 shares at December 31, 2025 to 10,673,993 at June 30, 2026. Share capital at par rose from CHF 2,253 thousand to CHF 2,263 thousand and share premium from CHF 481.9 million to CHF 483.6 million. Proceeds from the sale of treasury shares in public offerings, net of fees, were CHF 0.6 million in the period. Treasury shares are already issued shares held by the company; their sale can affect shares held by outside investors. They should not be equated with an unused authorisation to issue new shares.

An at-the-market programme with Jefferies LLC exists and is described in note 12 of the 2025 Form 20-F. The half-year statements refer to it only by cross-reference and disclose no at-the-market activity for the first half of 2026. That is a fact worth holding lightly: the absence of disclosed usage in a six-month interim statement is not the same as a commitment not to use it, and a company approaching a binary readout with a runway that ends in the fourth quarter of 2027 has an obvious reason to keep the facility available.

What dilution would look like from here

An equity raise would add shares according to the proceeds sought, issue price and transaction costs. The older August 11 illustration was not a financing plan. No new raise is assumed here; partnership receipts and treasury-share sales have different mechanics and should be assessed from their actual terms.

10 Governance: A Company Between Chief Executives

Andrea Pfeifer retired as CEO at the June 11, 2026 AGM following the May announcement. Board chair Martin Zügel is serving as interim CEO; the August 20 release still identifies him in that role. Leadership transition matters for development and financing decisions, but does not by itself establish a change in strategy.

The situation is worth weighing without dramatising it. A founder-led company that loses its founder after two decades faces a genuine transition, and the chair stepping into the executive seat is a common bridging arrangement that also concentrates board and management roles in one person for its duration. What makes the timing consequential here is what falls inside it: the full VacSYn Part 1 readout, the regulatory conversations about a registrational design that follow it, and any decision about partnering ACI-7104 or financing the company through 2027. Those are the decisions a permanent chief executive would normally own.

The counter-argument is equally factual. The strategy that produced the current position, meaning the pipeline focus initiative of the third quarter of 2025 and the partnering of the Alzheimer’s assets, was set before the transition and is visibly being executed: research spending down a third, two partner amendments signed in April 2026, a regulatory package delivered in August. Continuity of execution is visible in the filings; continuity of leadership is not yet settled.

11 Market Data And How This Stock Trades

Marketstack reports a September 4, 2026 close of $2.86 and volume of 155,628 shares, versus $2.93 on September 3. Finviz’s September 5 snapshot shows market capitalisation of $291.08 million. Quotes and provider ownership data are separate from the dated Swiss-franc financial statements.

ACIU is a small biotechnology company whose share price can react sharply to clinical news and financing. Its Swiss-franc accounts add currency effects for dollar-based comparisons. Near-term clinical guidance is expressed in windows, so an exact trading date cannot be inferred from the published schedule.

Cash and financial assets are balance-sheet resources consumed in development; they are not a floor under the share price. The historical dollar equivalents elsewhere use the explicitly dated August 11 exchange rate. Intangible assets are accounting carrying values, not estimates of sale proceeds.

12Retail sentiment

StockTwits connector snapshot, September 5, 2026: sentiment 41/100 (BEARISH), current message activity 23/100 (EXTREMELY LOW), 3,839 watchers. These are normalized platform scores, not probabilities or percentages of bullish/bearish messages. Tagged-message percentages were not usable. The low activity makes the discussion sensitive to a small number of posts; retail opinions are not clinical evidence.

StockTwits — $ACIU

13 The Case Made By Those Who Are Positive

What follows is the argument as its holders make it, not a Merlintrader view.

Immunogenicity supports further investigation. Interim antibody responses in serum and CSF support biological activity. They do not establish a clinical benefit, superiority to passive antibodies or the disappearance of competitive risk.

The safety profile is what an active immunotherapy needs. The theoretical objection to vaccinating against a normal human protein is autoimmunity. Across weeks 50 and 76 there were no clinically relevant or serious adverse events considered drug related, and the common events were injection-site reactions, headache and fatigue. That profile supports the long dosing intervals and the multi-year follow-up the Goradia grant now funds.

Three biomarkers moved in the same direction. CSF alpha-synuclein stabilised, neurofilament light stabilised where placebo rose, and plasma GFAP and DaT-SPECT both pointed the same way. Consistency across independent measures is harder to explain by chance than a single positive marker, which is the point Professor Poewe made when he called the consistency of the trends remarkable.

Regulatory access has improved. Fast Track offers additional opportunities for FDA interaction, and IND clearance permits US expansion. An agreed registrational design and the timing of any future approval remain unconfirmed.

Someone else pays for the Alzheimer’s half. Takeda funds ACI-24, Lilly funds the Tau small molecules, Janssen holds ACI-35. That structure produced CHF 16.2 million of first-half revenue, a $100.0 million upfront in 2024 and a $12.0 million milestone in April 2026, and it is why the share count has grown about 1.3% a year rather than the double digits typical of a company at this stage.

Partnership optionality remains relevant. Further milestones or a new agreement could extend funding, but contingent payments must not be counted as available cash. Market capitalisation less historical cash is not a standalone valuation of the pipeline.

14 The Case Made By Those Who Are Sceptical, And The Red Flags

Thirty-four patients. Part 1 randomised 34 people three to one, so the placebo arm is roughly eight or nine patients. Every biomarker and clinical comparison rests on that comparator. Trends that look clean at this size have repeatedly failed to replicate in Parkinson’s disease, where symptomatic variability is large and progression over eighteen months is modest even in untreated patients.

The efficacy analysis that matters most is post-hoc. The stabilisation of total CSF alpha-synuclein carries a p value of 0.018 from a post-hoc analysis. An analysis specified after seeing the data is a hypothesis, not a result, and regulators treat it accordingly.

The primary endpoints are not efficacy endpoints. VacSYn’s primary endpoints are safety and antibody titres. The clinical measure that would matter to a patient, MDS-UPDRS Part III, is secondary and the study was not designed to power it. A readout can therefore be reported as successful while leaving the central commercial question open, and the market may not price that distinction consistently.

Guidance has already moved. On December 11, 2025 final Part 1 data were expected in mid-2026. In the August 5, 2026 release the same data set is guided to the second half of 2026. A slip of that size in a trial that stopped recruiting some time ago is not alarming on its own, but it is a fact, and the two August documents describe the endpoint as week 104 and week 100 respectively, which is an inconsistency in the company’s own disclosure.

The company is being run on an interim basis. The founder chief executive retired at the June 11, 2026 annual general meeting and the chair holds the executive seat while a search continues. The registrational strategy, any partnering of ACI-7104 and any financing decision fall inside that interval.

Further development may require additional capital. Management estimates funding into Q4 2027. A larger or longer trial could require partnership proceeds, equity or another financing source; the amount and timing depend on a development plan that has not been established here.

Partner money can stop. Takeda may terminate the option and licence agreement at any time on ninety days’ notice. The revenue line that carried the first half of 2026 is composed of two non-recurring payments from two counterparties, and there is no product revenue underneath it.

Currency and disclosure timing matter. Swiss-franc results require dated conversion for dollar comparisons. AC Immune provides interim corporate and financial updates in addition to its formal annual and half-year statements; investors should consult new 6-K filings rather than assume a fixed two-release calendar.

15 Scenario Framework

The two paths below are descriptions of what would have to happen, not forecasts, and they carry no probabilities and no price levels.

The main distinction is whether biological signals translate into reproducible, clinically meaningful outcomes and a fundable development plan. See the catalyst section for current windows. No exact next earnings date has been confirmed in this review; the March 13, 2026 release concerned FY2025, not FY2026.

16 Bottom Line

Two accurate and opposite descriptions of AC Immune can be held at the same time. The first is a company that has demonstrated, for the first time in Parkinson’s disease, that an active immunotherapy raises antibodies which reach the central nervous system at more than 500 times placebo levels with a 100% responder rate, that three independent biomarkers moved consistently in the direction of stabilisation, that the FDA has now granted Fast Track and cleared an IND, and that three large pharmaceutical partners fund the rest of the pipeline while the share count grows about 1.3% a year. The second is a company with no product, no revenue that is not a partner payment, a placebo arm of roughly eight patients underneath its central efficacy claim, a post-hoc p value on its most quoted biomarker result, an interim chief executive, a readout window that has already moved once, and cash that runs out in the fourth quarter of 2027. Both descriptions come from the same filings.

What is verified. Fast Track designation and IND clearance for ACI-7104 in early Parkinson’s disease, announced August 11, 2026 and furnished on Form 6-K the same day. Interim Part 1 results at week 76 in 34 randomised patients: 100% immunogenicity responder rate, serum and CSF antibody titres more than 500-fold above placebo, Spearman correlation between compartments of 0.92 at week 24 and 0.85 at week 76, CSF alpha-synuclein stabilisation with a post-hoc p of 0.018, stable neurofilament light against a rising placebo arm, no clinically relevant drug-related serious adverse events, injection-site reactions in 56% of patients. Cash resources of CHF 75.4 million at June 30, 2026, about $93.0 million, composed of CHF 27.8 million cash and CHF 47.6 million short-term financial assets, funding operations into Q4 2027 on the company’s own statement and excluding milestone payments. First-half revenue of CHF 16.2 million, all from Lilly and Takeda, against CHF 2.3 million a year earlier. Research and development of CHF 22.2 million, down from CHF 32.7 million. Net loss of CHF 12.9 million, CHF 0.13 per share. 101,742,231 shares outstanding at December 31, 2025 per the Form 20-F, and 10,673,993 treasury shares at June 30, 2026.

What is not verified. Whether the week-100 data set reproduces the week-76 separation. What registrational design, if any, the FDA has indicated it would accept. Whether the endpoint of the final Part 1 analysis is week 100 or week 104, since the company used both descriptions in documents six days apart. The point-in-time share count at June 30, 2026, which the interim statements do not restate. Any use of the at-the-market programme in 2026, which is referred to only by cross-reference to the 20-F. Who will be the permanent chief executive, and when. And the analyst consensus, since no individual note could be confirmed with both house and exact date.

The current development windows are listed in the catalyst section. They are company guidance, not guaranteed dates. The stated Q4 2027 funding horizon is an estimate rather than a fixed date on which cash becomes zero.