SPTX 10-K & 10-Q changes, risk factors and insider trading

The success of our business depends primarily upon our ability to identify, develop, and commercialize product candidates based on our Glyph platform. We do not know whether we will be able to develop any product candidates that succeed through clinical development or to develop products of commercial value. We have no products approved for commercial sale and have not generated any revenue from product sales or collaboration arrangements to date. We will continue to incur significant research and development and other expenses related to our preclinical and clinical development and ongoing operations. As a result, we are not profitable and have incurred losses in each period since our inception. Net losses and negative cash flows have had, and will continue to have, an adverse effect on our stockholders’ equity and working capital. Our net losses totaled $25.4$88.0 million and $13.1$28.2 million for the threesix months ended MarchJune 31,30, 2026 and 2025, respectively. As of MarchJune 31,30, 2026, we have not yet generated product or collaboration revenue and had an accumulated deficit of $139.5$202.1 million. We expect to continue to incur significant losses for the foreseeable future, and we expect these losses to increase as we continue our research and development of, and seek regulatory approvals for, our product candidates. The success of our product candidates will depend on several factors, including the following:

As of MarchJune 31,30, 2026, we had $212.6$427.3 million of cash, cash equivalents and investments. Based upon our current operating plan, we believe that our existing cash, cash equivalents, and investments, together with the net proceeds from our IPO, will enable us to fund our operating expenses and capital expenditure requirements into 2029. We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we expect. We may also raise additional financing on an opportunistic basis in the future. For example, we may seek additional capital due to favorable market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. Attempting to secure additional financing may divert our management from our day-to-day activities, which may adversely affect our ability to develop our product candidates. Our future capital requirements will depend on many factors, including but not limited to:

We have never commercialized a product, and even if any of our product candidates are approved by the appropriate regulatory authorities for marketing and sale, it may nonetheless fail to achieve sufficient market acceptance by physicians, patients, third-party payors and others in the medical community. The commercial success of any of our product candidates will depend significantly on the broad adoption and use of the resulting product by these individuals and organizations for approved indications. For example, Glyph2BLSDTM,Glyph2BLSD, in development for the treatment of depressive disorders, including treatment-resistant depression, or TRD, post-traumatic stress disorder, or PTSD,neuropsychiatric and headache disorders,disorders with significant unmet need, is a Glyphed oral prodrug of the non-hallucinogenic neuroplastogen, 2-bromo-LSD. There has been recent interest in psychedelics in part because of their potential to demonstrate therapeutic effects in neuropsychiatric disorders. Although Glyph2BLSD is not a psychedelic, there is a risk that it will be viewed as such by investors and the public, or could be classified as such by regulatory authorities based on its final structure. Treatments containing controlled substances or drugs that have similar effects or characteristics of controlled substances may generate public controversy or unfavorable views, which could lead to delays in, and increased expenses for, and limit or restrict the introduction and marketing of such types of therapeutic candidates. For more information on controlled substances, see subsection titled “—Certain of our product candidates may be regulated as controlled substances, the making, use, sale, importation, exportation, and distribution of which are subject to significant regulation by the U.S. Drug Enforcement Administration and other regulatory agencies.”

As of MarchJune 31,30, 2026, we had 58 full-time employees. We expect to experience significant growth in the number of our employees and the scope of our operations over time. To manage these growth activities, we must continue to implement and improve our managerial, operational, quality, and financial systems, expand our facilities and continue to recruit and train additional qualified personnel. Our management may need to devote a significant amount of its attention to managing these growth activities. Due to our limited financial resources and the limited experience of our management team in managing a company with such anticipated growth, we may not be able to effectively manage the expansion or relocation of our operations, retain key employees, or identify, recruit, and train additional qualified personnel. Our inability to manage the expansion or relocation of our operations effectively may result in weaknesses in our infrastructure, give rise to operational mistakes, loss of business opportunities, loss of employees and reduced productivity among remaining employees. Our expected growth could also require significant capital expenditures and may divert financial resources from other projects, such as the development of additional product candidates. If we are unable to effectively manage our expected growth, our expenses may increase more than expected, our ability to generate revenues could be reduced and we may not be able to implement our business strategy, including the successful commercialization of our product candidates.

In addition, in the future, we may issue additional shares of common stock, or other equity or debt securities convertible into common stock, in connection with a financing, acquisition, employee arrangement, or otherwise. Any such issuance could result insubstantialin substantial dilution to our existing stockholders and could cause the price of our common stock to decline.

If we fail to keep pace with rapidly evolving AI Technologies, especially in the medical device industry, our competitive position and business results may suffer. The introduction and use of AI Technologies, particularly generative AI, into new or existing offerings may result in new or expanded risks and liabilities, including due to enhanced governmental or regulatory scrutiny, litigation, compliance issues, ethical concerns, confidentiality or security risks, as the well as other factors that could adversely affect our reputation, as the well as our business, operating results, and financial condition. For example, AI Technologies can lead to unintended consequences, including generating content that appears correct but is factually inaccurate, misleading, or otherwise flawed, which could negatively impact our customers, harm our reputation and business, and expose us to liability.

You should read the following discussion and analysis of our financial condition and results of operations in conjunction with our condensed consolidated financial statements and related notes appearing elsewhere in this Quarterly Report on Form 10-Q and our audited consolidated financial statements and related notes included in our final prospectus for our initial public offering ("IPO") filed with the SEC pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended (the “Securities Act”) on May 1, 2026 (the “IPO Prospectus”). References to the "Company," “Seaport,” "Seaport Therapeutics," “we,” “our,” “us,” or similar terms refer to Seaport Therapeutics, Inc. and its wholly owned subsidiaries, or either or all of them as the context may require. This discussion and analysis and other parts of this Quarterly Report on Form 10-Q contain forward-looking statements based upon our current plans and expectations that involve risks, uncertainties and assumptions, such as statements regarding our plans, strategies, objectives, expectations, intentions, and beliefs. Our actual results and the timing of events could differ materially from those anticipated in these forward-looking statements as a result of various factors, including those set forth under “Risk Factors” and elsewhere in this Quarterly Report on Form 10-Q. You should carefully read the sections entitled “Risk Factors” and “Special Note Regarding Forward-Looking Statements” to gain an understanding of the important factors that could cause actual results to differ materially from our forward-looking statements.

Our lead product candidate, GlyphAllo ("Glyph Allopregnanolone"), is a novel, Glyphed oral prodrug of allopregnanolone, an endogenous molecule that has been clinically validated in two third-party trials in the United States for the treatment of postpartum depression, or PPD, a form of major depressive disorder, or MDD, as a rapidly acting antidepressant with anxiolytic and sleep-promoting effects. We have initiated the Phase 2b BUOY-1 trial in patients with MDD with or without anxious distress and anticipate topline data in the first half of 2027. GivenWe the strength in enrollment andcontinue to maximize the likelihood that the BUOY-1 trial could be used to support registration, we plan to enroll the full prespecified target sample size of approximately 360 patients and no longer intend to perform a sample size re-estimation (SSRE). We have dosed the first patient inadvance a Phase 1 driving simulation trial of GlyphAllo, with topline data expected in the second half of 2026, in advance of the expected topline readout of the BUOY-1 trial.

Our second product candidate, GlyphAgo ("Glyph Agomelatine"), is a novel, Glyphed oral prodrug of agomelatine, a clinically validated anxiolytic and antidepressant that is approved for the treatment of generalized anxiety disorder, or GAD, in Australia and MDD in Australia and the European Union, or EU. In April 2026, we reported topline data from the single-ascending dose, or SAD, and crossover portions of our Phase 1 proof-of-concept clinical trial for GlyphAgo. In the head-to-head crossover portion of the trial, GlyphAgo demonstrated a 6.8-fold increase in bioavailability of agomelatine compared to unmodified orally administered agomelatine, and showed significantly lower (10-fold) pharmacokinetic variability compared to unmodified agomelatine. In the SAD portion of the trial, GlyphAgo demonstrated a 9.6 to 14.5-fold increase in dose-normalized exposure compared to agomelatine. GlyphAgo was well-tolerated and no liver-related adverse events were observed. In June 2026, we reported topline data from the multiple-ascending dose, or MAD, portion of the trial, which showed that seven-day dosing of GlyphAgo achieved therapeutic exposures of agomelatine at doses projected to avoid liver enzyme elevations and reduce or eliminate the need for liver function testing, and demonstrated favorable safety and tolerability, with no liver-related adverse events observed. We plan to initiate a Phase 2a proof-of-pharmacology trial designed to evaluate the potential sleep benefit of GlyphAgo in patients with GAD and sleep disturbance,disturbance in the second half of 2026, with topline data expected in early 2028 and, in parallel, initiate a Phase 2b trial designed to evaluate the efficacy and safety of GlyphAgo in patients with GAD,GAD in the first half of 2027, with topline data expected by the end of 2028.

We are also advancing Glyph2BLSD (Glyph 2-bromo-LSD), a novel, Glyphed oral prodrug of the non-hallucinogenic LSD analog 2-bromo-LSD, in preclinical studies for depressive disorders, including treatment-resistant depression, or TRD, post-traumatic stress disorder, or PTSD,neuropsychiatric and headache disorders.disorders with significant unmet need.

We have devoted substantially all of our efforts to organizing and staffing our company, business planning, capital raising, research and development activities, building and strengthening our intellectual property portfolio, and providing general and administrative support for these operations. We have funded our operations with proceeds from the issuance and sale of convertible preferred stock, including the $100.1 million gross proceeds we received in April 2024 from our Series A-2 Financing and the $226.0 million gross proceeds we received in October 2024 from our Series B Financing. During the second quarter of 2026, we completed our IPO, in which we sold an aggregate 14,446,658 shares of our common stock, including 286,568 shares issued pursuant to the exercise of the underwriters' overallotment option,stock at a public offering price of $18.00 per shareshare, resulting in aggregate net proceeds of approximately $238.7$238.4 million, after deducting underwriterunderwriting discounts, commissions and other estimated offering expenses.

We have incurred significant operating losses since the inception of our business and expect to continue to generate operating losses for the foreseeable future, and expect that our expenses and operating losses will continue to increase substantially. Our ability to generate product revenue sufficient to achieve profitabilityprofitability, if ever, will depend on the successful development and eventual commercialization of any product candidates we may develop. During the threesix months ended MarchJune 31,30, 2026 and 2025, we had a net loss of $25.4$88.0 million and $13.1$28.2 million, respectively. As of MarchJune 31,30, 2026, we had an accumulated deficit of $139.5$202.1 million. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of our preclinical studies and planned clinical trials and our expenditures on other research and development activities.

As of MarchJune 31,30, 2026, we had cash, cash equivalents and investments of $212.6$427.3 million. Based on our current operating plans, we believe that our existing cash, cash equivalents and investments, together with the net proceeds from our IPO completed during the second quarter of 2026,investments will be sufficient to fund our operating expenses and capital expenditure requirements into 2029.

General and administrative expenses consist of salaries and personnel-related costs, including stock-based compensation expense, for our personnel in executive, business development, legal, finance and accounting, human resources and other administrative functions, consulting fees, facility costs not otherwise included in R&D expenses, fees paid for accounting and tax services, insurance expenses, costs to maintain compliance as a public company and legal costs consisting of general corporate legal fees and patent legal fees.

We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support the expansion of our business, particularly in support of development of product candidates and our continued research and clinical development activities. We will also incur significant costs associated with being a public company, including increased accounting, audit, legal, regulatory, compliance, and director and officer insurance costs, as well as expenses related to services associated with maintaining compliance with the requirements of the Nasdaq Stock Market, the Securities and Exchange Commission, and investor relations costs.

Provision for income taxes consists of United States federal and state income taxes in jurisdictions in which we conduct business and foreign income taxes related to our Australian subsidiary. The provision for income taxes is based on our taxable income.income in Australia. Our loss before income taxes is adjusted for permanent and temporary tax differences, primarily related to capitalized non-U.S. research and development expenses, resulting in taxable income or loss. We have no benefit (losses) recorded in the U.S. as we have recorded a full valuation allowance of our U.S. deferred tax asset position as of MarchJune 31,30, 2026 and 2025 as we believe it was more likely than not that we would not be able to utilize our deferred tax assets.

Comparison of the three months ended MarchJune 31,30, 2026 and 2025

Research and development expenses increased by $10.9$11.2 million from $10.5$13.4 million for the three months ended MarchJune 31,30, 2025 to $21.4$24.6 million for the three months ended MarchJune 31,30, 2026. The increase in research and development expenses was primarily attributable to:

$5.0$8.0 million of increased costs associated with our lead program GlyphAllo, which was primarily due to the advancement of our Phase 2b BUOY-1 trial which commenced in July 2025 and other supporting clinical studies;

$4.5$1.5 million of increased costs associated with our GlyphAgo program, which was primarily due to advancement of our Phase 1 trial, for which we announced dosing of the first participant in September 2025 and completed the study in the second quarter of 20262026, and other development activities as we advance the program;

$0.3$0.1 million of decreasedincreased costs associated with our Glyph2BLSD program due to timing of our researchdevelopment activities.activities;

General and administrative expenses increased by $0.5$36.1 million from $5.7$5.1 million for the three months ended MarchJune 31,30, 2025 to $6.1$41.2 million for the three months ended MarchJune 31,30, 2026. The increase in general and administrative expenses was primarily attributable to:

$0.7$0.9 million of decreasedincreased professional fees primarily due to lowerhigher auditaudit, legal, and legalconsulting fees.fees as a result of operating as a public company;

Other income, netnet, decreased by $0.4$0.1 million from $3.1$3.5 million for the three months ended MarchJune 31,30, 2025 to $2.7$3.5 million for the three months ended MarchJune 31,30, 2026. The decrease in other income, net was primarily attributed to decreasean increase in interest income on our investments and cash equivalents due to the amountinvestment of funds investedreceived from our IPO in interestMay bearing accounts,2026, offset by ana increasedecrease in our research and development tax credit asfrom a result ofour qualifying research and development spend in Australia.

Income tax provision increased by $0.5$0.1 million from $0.0$0.1 million for the three months ended MarchJune 31,30, 2025 to $0.5$0.3 million for the three months ended MarchJune 31,30, 2026. The increase in the income tax provision was attributed to foreign income taxes related to our Australian subsidiary primarily as a result of our research and development tax credit inand Australia.transfer pricing agreement with Seaport Therapeutics, Inc.

Since our inception, we have incurred significant operating losses. During the threesix months ended MarchJune 31,30, 2026 and 2025, we had a net loss of $25.4$88.0 million and $13.1$28.2 million, respectively. As of MarchJune 31,30, 2026, we had an accumulated deficit of $139.5$202.1 million. We have not generated any revenue from product sales and we do not expect to generate revenue from sales of products in the near term, if at all. We expect to incur significant expenses and operating losses for the foreseeable future as we advance our product candidates into and through clinical development and as we continue to develop additional product candidates. As such, we expect our research and development and general and administrative costs to continue to increase significantly, including the costs associated with operating as a public company.

To date, prior to our initial public offering,date we have funded our operations with the aggregate gross proceeds of $326.1 million from the Series A and Series B Financings.Financings During the second quarter of 2026, we raisedand aggregate net proceeds of $238.7$238.4 million from the sale of shares of common stock in our initial public offering,IPO, after deducting underwriterunderwriting discounts, commissions and other estimated offering expenses. As of MarchJune 31,30, 2026, we had cash, cash equivalents and investments of $212.6$427.3 million. Based on our current operating plans, we believe that our existing cash, cash equivalents and investments, together with the net proceeds from our IPO completed during the second quarter of 2026,investments will be sufficient to fund our operating expenses and capital expenditure requirements into 2029.

Net cash used in operating activities was $20.2$46.3 million for both the threesix months ended MarchJune 31,30, 2026 and $35.5 million for the six months ended June 30, 2025, respectively. Cash used in operating activities wasincreased unchangedby $10.8 million due to an increase in our operating expenses for the threesix months ended MarchJune 31,30, 2026, offset by a reductionchanges in prepaidoperating deposits for our clinical development activitiesassets and liabilities including an increase in our accounts payables balance due to timing of payments.

Net Cash Used in by FinancingInvesting Activities

Net cash usedprovided inby financing activities was $0.8$240.1 million for the threesix months ended MarchJune 31,30, 2026, primarily consisting of paymentsnet ofproceeds deferredfrom offeringour costs.IPO. There were no cash flows from financing activities for the threesix months ended MarchJune 31,30, 2025.

As of MarchJune 31,30, 2026, we had cash andcash, cash equivalents,equivalents and investments of $212.6$427.3 million. Based upon our current operating plans, we believe that the net proceeds from our initial public offering completed during the second quarter of 2026, together with our cash, cash equivalents and investments as of MarchJune 31,30, 2026, will be sufficient to fund our operations into 2029. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect.

As of MarchJune 31,30, 2026, the first two development milestones forunder athe totalMonash ofLicense Agreement, totaling $0.2 millionmillion, werehad been achieved and were paid by PureTechPureTech, as they occurred prior to our formation,formation. and weWe have since paid the third development milestone of $0.1 millionmillion, as well as annual maintenance fees. No other milestonesmilestone payments have occurredbecome due or have been paid under the Monash License Agreement as of MarchJune 31,30, 2026.

In December 2024, we entered into a laboratory license with a third party for lab space located in Boston, Massachusetts. The license commenced in January 2025 and iswas for an initial term of 24 months from the commencement date. The aggregate payments under the full license total approximately $1.2 million. In March 2026, we exercised our option to extend the lease for an additional 12 months. The modification resulted in an increase in the aggregate payments under the full license total approximately $0.6 million.

For additional information on our contractual obligation and commitments please see Note 8—Monash License Agreementand Collaboration Agreements and Note 14—Commitments and Contingencies.

Our significant accounting policies are described in more detail in Note 2 to our consolidated financial statements included in our IPO prospectus. During the threesix months ended MarchJune 31,30, 2026, there were no material changes to our critical accounting policies and estimates described under Management’s Discussion and Analysis of Critical Accounting Policies and Estimates which are included in our IPO Prospectus, except that our common stock is now publicly traded and we therefore no longer require common stock valuations.