Seaport Therapeutics, Inc.

Previous wording

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 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.

Current wording

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.

Previous wording

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. Given the strength in enrollment and 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 in 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.

Current wording

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. We continue to advance 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.

Previous wording

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, with topline data expected in early 2028 and, in parallel, a Phase 2b trial designed to evaluate the efficacy and safety of GlyphAgo in patients with GAD, with topline data expected by the end of 2028.

Current wording

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 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 in the first half of 2027, with topline data expected by the end of 2028.

Previous wording

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, and headache disorders.

Current wording

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 neuropsychiatric and headache disorders with significant unmet need.

Previous wording

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, at a public offering price of $18.00 per share resulting in aggregate net proceeds of approximately $238.7 million, after deducting underwriter discounts, commissions and other estimated offering expenses.

Current wording

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 at a public offering price of $18.00 per share, resulting in aggregate net proceeds of approximately $238.4 million, after deducting underwriting discounts, commissions and other offering expenses.

Previous wording

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 profitability will depend on the successful development and eventual commercialization of any product candidates we may develop. During the three months ended March 31, 2026 and 2025, we had a net loss of $25.4 million and $13.1 million, respectively. As of March 31, 2026, we had an accumulated deficit of $139.5 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.

Current wording

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 profitability, if ever, will depend on the successful development and eventual commercialization of any product candidates we may develop. During the six months ended June 30, 2026 and 2025, we had a net loss of $88.0 million and $28.2 million, respectively. As of June 30, 2026, we had an accumulated deficit of $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.

Previous wording

As of March 31, 2026, we had cash, cash equivalents and investments of $212.6 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, will be sufficient to fund our operating expenses and capital expenditure requirements into 2029.

Current wording

As of June 30, 2026, we had cash, cash equivalents and investments of $427.3 million. Based on our current operating plans, we believe that our existing cash, cash equivalents and investments will be sufficient to fund our operating expenses and capital expenditure requirements into 2029.

Previous wording

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, legal costs consisting of general corporate legal fees and patent legal fees.

Current wording

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.

Previous wording

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.

Current wording

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.

Previous wording

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. 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 recorded a full valuation allowance of our U.S. deferred tax asset position as of March 31, 2026 and 2025 as we believe it was more likely than not that we would not be able to utilize our deferred tax assets.

Current wording

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 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 June 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.

Previous wording

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

Current wording

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

Previous wording

$4.5 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 2026;

Current wording

$1.5 million of increased costs associated with our GlyphAgo program, which was primarily due to 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 2026, and other development activities as we advance the program;

Previous wording

$1.1 million of increased costs associated with employee compensation primarily due to increased headcount to support our research and development operations; and

Current wording

$0.7 million of increased costs associated with employee compensation primarily due to increased headcount to support our research and development operations and salary adjustments; and

Previous wording

$0.4 million of increased costs associated with stock-based compensation costs primarily due to additional equity grants issued under our 2024 Equity Plan, partially offset by;

Current wording

$0.3 million of increased costs associated with non-cash stock-based compensation costs primarily due to additional equity grants issued under our 2024 and 2026 Equity Plan.

Previous wording

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

Current wording

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

Previous wording

$0.5 million of increased employee compensation, excluding stock-based compensation due to increased headcount to support our operations; and

Current wording

$0.1 million of increased employee compensation due to salary adjustments.

Previous wording

Income tax provision increased by $0.5 million from $0.0 million for the three months ended March 31, 2025 to $0.5 million for the three months ended March 31, 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 in Australia.

Current wording

Income tax provision increased by $0.1 million from $0.1 million for the three months ended June 30, 2025 to $0.3 million for the three months ended June 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 and transfer pricing agreement with Seaport Therapeutics, Inc.

Previous wording

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

Current wording

$13.0 million of increased costs associated with our lead program GlyphAllo, which was primarily due to advancement of our Phase 2b BUOY-1 trial which commenced in July 2025 and other supporting clinical studies;

Previous wording

$0.3 million of decreased costs associated with our Glyph2BLSD program due to timing of our research activities.

Current wording

$0.2 million of decreased costs associated with our Glyph2BLSD program due to timing of our development activities.

Previous wording

Other income, net decreased by $0.4 million from $3.1 million for the three months ended March 31, 2025 to $2.7 million for the three months ended March 31, 2026. The decrease in other income, net was primarily attributed to decrease in interest income on our investments and cash equivalents due to the amount of funds invested in interest bearing accounts, offset by an increase in our research and development tax credit as a result of qualifying research and development spend in Australia.

Current wording

Other income, net decreased by $0.5 million from $6.6 million for the six months ended June 30, 2025 to $6.1 million for the six months ended June 30, 2026. The decrease in other income, net was primarily attributed to decrease in interest income on our investments and cash equivalents due to the amount of funds invested in interest bearing accounts, offset by an increase in our research and development tax credit as a result of qualifying research and development spend in Australia.

Previous wording

Since our inception, we have incurred significant operating losses. During the three months ended March 31, 2026 and 2025, we had a net loss of $25.4 million and $13.1 million, respectively. As of March 31, 2026, we had an accumulated deficit of $139.5 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.

Current wording

Since our inception, we have incurred significant operating losses. During the six months ended June 30, 2026 and 2025, we had a net loss of $88.0 million and $28.2 million, respectively. As of June 30, 2026, we had an accumulated deficit of $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.

Previous wording

To date, prior to our initial public offering, we have funded our operations with the aggregate gross proceeds of $326.1 million from the Series A and Series B Financings. During the second quarter of 2026, we raised aggregate net proceeds of $238.7 million from the sale of shares of common stock in our initial public offering, after deducting underwriter discounts, commissions and other estimated offering expenses. As of March 31, 2026, we had cash, cash equivalents and investments of $212.6 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, will be sufficient to fund our operating expenses and capital expenditure requirements into 2029.

Current wording

To date we have funded our operations with the aggregate gross proceeds of $326.1 million from the Series A and Series B Financings and aggregate net proceeds of $238.4 million from the sale of shares of common stock in our IPO, after deducting underwriting discounts, commissions and other offering expenses. As of June 30, 2026, we had cash, cash equivalents and investments of $427.3 million. Based on our current operating plans, we believe that our existing cash, cash equivalents and investments will be sufficient to fund our operating expenses and capital expenditure requirements into 2029.

Previous wording

Net cash used in operating activities was $20.2 million for both the three months ended March 31, 2026 and 2025, respectively. Cash used in operating activities was unchanged due to an increase in our operating expenses for the three months ended March 31, 2026, offset by a reduction in prepaid deposits for our clinical development activities and an increase in our accounts payables balance due to timing of payments.

Current wording

Net cash used in operating activities was $46.3 million for the six months ended June 30, 2026 and $35.5 million for the six months ended June 30, 2025, respectively. Cash used in operating activities increased by $10.8 million due to an increase in our operating expenses for the six months ended June 30, 2026, offset by changes in operating assets and liabilities including an increase in our accounts payables balance due to timing of payments.

Previous wording

Net Cash Provided by (Used in) Investing Activities

Current wording

Net Cash Used in Investing Activities

Previous wording

Net cash used in financing activities was $0.8 million for the three months ended March 31, 2026, consisting of payments of deferred offering costs. There were no cash flows from financing activities for the three months ended March 31, 2025.

Current wording

Net cash provided by financing activities was $240.1 million for the six months ended June 30, 2026, primarily consisting of net proceeds from our IPO. There were no cash flows from financing activities for the six months ended June 30, 2025.

Previous wording

As of March 31, 2026, we had cash and cash equivalents, and investments of $212.6 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 March 31, 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.

Current wording

As of June 30, 2026, we had cash, cash equivalents and investments of $427.3 million. Based upon our current operating plans, we believe our cash, cash equivalents and investments as of June 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.

Previous wording

As of March 31, 2026, the first two development milestones for a total of $0.2 million were achieved and paid by PureTech as they occurred prior to our formation, and we have paid the third development milestone of $0.1 million as well as annual maintenance fees. No other milestones have occurred or have been paid under the Monash License Agreement as of March 31, 2026.

Current wording

As of June 30, 2026, the first two development milestones under the Monash License Agreement, totaling $0.2 million, had been achieved and were paid by PureTech, as they occurred prior to our formation. We have since paid the third development milestone of $0.1 million, as well as annual maintenance fees. No other milestone payments have become due or been paid under the Monash License Agreement as of June 30, 2026.

Previous wording

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 is 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.

Current wording

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 was 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.

Previous wording

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

Current wording

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

Previous wording

Our significant accounting policies are described in more detail in Note 2 to our consolidated financial statements included in our IPO prospectus. During the three months ended March 31, 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.

Current wording

Our significant accounting policies are described in more detail in Note 2 to our consolidated financial statements included in our IPO prospectus. During the six months ended June 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.