Alto Neuroscience, Inc.

Previous wording

ALTO-203 is an investigational novel, oral, small molecule histamine H3 inverse agonist. We are currently advancing ALTO-203 for the treatment of patients with MDD associated with increased levels of anhedonia.

Current wording

ALTO-203 is an investigational novel, oral, small molecule histamine H3 inverse agonist.

Previous wording

An exploratory Phase 2 POC trial, which enrolled 69 patients, was conducted in two sequential, double-blind, placebo-controlled periods and resulted in the identification of a patient selection biomarker and positive pharmacodynamic results. The trial was designed to characterize the pharmacodynamic, pharmacokinetic, safety, and tolerability profile of ALTO-203 across two dose levels compared to placebo in a crossover design and was not powered to detect statistical significance on traditional depression outcome scales (e.g., MADRS).

Current wording

An exploratory Phase 2 POC trial, which enrolled 69 patients with MDD associated with increased levels of anhedonia, was conducted in two sequential, double-blind, placebo-controlled periods and resulted in the identification of a patient selection biomarker and positive pharmacodynamic results. The trial was designed to characterize the pharmacodynamic, pharmacokinetic, safety, and tolerability profile of ALTO-203 across two dose levels compared to placebo in a crossover design and was not powered to detect statistical significance on traditional depression outcome scales (e.g., MADRS).

Previous wording

We have not generated any revenue from product sales and we have incurred recurring losses since our inception. Our net losses were $27.6 million and $53.9 million for the three and six months ended June 30, 2026, respectively. Our net losses were $17.7 million and $32.9 million for thethree and six months ended June 30, 2025, respectively. As of June 30, 2026, we had an accumulated deficit of $255.5 million. We expect to continue to generate operating losses and negative operating cash flows for the foreseeable future. We anticipate that our operating expenses and capital expenditures will increase substantially with our ongoing activities, particularly as we:

Current wording

We have not generated any revenue from product sales and we have incurred recurring losses since our inception. Our net losses were $25.1 million and $79.0 million for the three and nine months ended September 30, 2026, respectively. Our net losses were $14.2 million and $47.1 million for thethree and nine months ended September 30, 2025, respectively. As of September 30, 2026, we had an accumulated deficit of $280.6 million. We expect to continue to generate operating losses and negative operating cash flows for the foreseeable future. We anticipate that our operating expenses and capital expenditures will increase substantially with our ongoing activities, particularly as we:

Previous wording

As of June 30, 2026, we had cash, cash equival ents and restricted cash of $244.2 million, and we raised approximately $94.6 million in July 2026 Offering (defined below). We believe that our existing cash and cash equivalents, together with the net proceeds of the July 2026 Offering and the anticipated proceeds under our Convertible Grant Agreement with Wellcome, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 12 months. See “—Liquidity and Capital Resources.”

Current wording

As of September 30, 2026, we had cash, cash equival ents and restricted cash of $319.8 million. We believe that our existing cash and cash equivalents, together with the anticipated proceeds under our Convertible Grant Agreement with Wellcome, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 12 months. See “—Liquidity and Capital Resources.”

Previous wording

Research and development expenses were $22.1 million for the three months ended June 30, 2026, compared to $13.1 million for the three months ended June 30, 2025. Increases in research and development expenses were due primarily to:

Current wording

Research and development expenses were $18.2 million for the three months ended September 30, 2026, compared to $10.5 million for the three months ended September 30, 2025. Increases in research and development expenses were due primarily to:

Previous wording

•an increase of approximately $6.4 million in expenses related to development of our ALTO-207 program, whichwe acquired in May 2025. The costs are primarily related to clinical and manufacturing activities required to launch the Phase 2b clinical trial, which we initiated in April 2026.

Current wording

•an increase of approximately $6.9 million in expenses related to development of ALTO-207, whichwe acquired in May 2025. The costs are primarily related to our Phase 2b clinical trial, which we initiated in April 2026, and manufacturing activities.

Previous wording

•an increase of $1.4 million in salary and personnel related costs, which includes $0.9 million of increased non-cash stock-based compensation.

Current wording

•an increase of $1.6 million in salary and personnel related costs, which includes $0.6 million of increased non-cash stock-based compensation.

Previous wording

•an increase of approximately $1.0 million in expenses related to the development of our ALTO-101 program, including our Phase 2 POC trial of ALTO-101 for which we announced top line data on April 1, 2026.

Current wording

Increases in research and development expenses were partially offset by a $1.0 million decrease in expenses related to the development of ALTO-101, including our Phase 2 POC trial of ALTO-101 for which we announced top line data in April 2026.

Previous wording

General and administrative expenses were $7.0 million for the three months ended June 30, 2026, compared to $5.6 million for the three months ended June 30, 2025. The increase of $1.5 million was primarily due to increases in professional fees.

Current wording

General and administrative expenses were $9.1 million for the three months ended September 30, 2026, compared to $4.4 million for the three months ended September 30, 2025. The increase of $4.6 million was primarily due to increases in personnel costs and professional fees.

Previous wording

Other income, net increased $0.5 million during the three months ended June 30, 2026, compared to the three months ended June 30, 2025. The increase was primarily due to the increase in interest income of $0.4 million during the three months ended June 30,2026 compared to the three months ended June 30, 2025.

Current wording

Other income, net increased $1.3 million during the three months ended September 30, 2026, compared to the three months ended September 30, 2025. The increase was primarily due to the increase in interest income of $1.1 million during the three months ended September 30, 2026 compared to the three months ended September 30, 2025.

Previous wording

The following table summarizes our results of operations for the sixmonths ended June 30, 2026 and 2025 (in thousands):

Current wording

The following table summarizes our results of operations for the nine months ended September 30, 2026 and 2025 (in thousands):

Previous wording

Research and development expenses were $42.4 million for the six months ended June 30, 2026, compared to $23.1 million for the six months ended June 30, 2025. The increase in research and development costs was due to:

Current wording

Research and development expenses were $60.6 million for the nine months ended September 30, 2026, compared to $33.6 million for the nine months ended September 30, 2025. The increase in research and development costs was due to:

Previous wording

•an increase of approximately $10.5 million in expenses related to development of ALTO-207, whichwe acquired in May 2025. The costs are primarily related to clinical and manufacturing activities required to launch the Phase 2b clinical trial, which we initiated in April 2026.

Current wording

•an increase of approximately $17.4 million in expenses related to development of ALTO-207, whichwe acquired in May 2025. The costs are primarily related to clinical and manufacturing activities required to launch the Phase 2b clinical trial, as well as our ongoing Phase 2b clinical trial which we initiated in April 2026.

Previous wording

•an increase of approximately $5.4 million in expenses related to the development of ALTO-101, including our Phase 2 POC trial of ALTO-101 for which we announced top line data on April 1, 2026.

Current wording

•an increase of approximately $4.3 million in expenses related to the development of ALTO-101, including our Phase 2 POC trial of ALTO-101 for which we announced top line data on April 1, 2026.

Previous wording

•an increase of approximately $2.9 million in expenses related to the ongoing development of ALTO-100 and ALTO-300.

Current wording

•an increase of approximately $3.2 million in expenses related to the ongoing development of ALTO-100 and ALTO-300.

Previous wording

•an increase of approximately $2.6 million in salary and personnel related costs due to increased headcount as well as $1.5 million of non-cash stock-based compensation.

Current wording

•an increase of approximately $4.2 million in salary and personnel related costs due to increased headcount as well as $2.1 million of increased non-cash stock-based compensation.

Previous wording

•a decrease of approximately $1.3 million in clinical development related expenses primarily driven by the completion of the ALTO-203 Phase 2 POC clinical trial; and

Current wording

•a decrease of approximately $1.5 million in clinical development related expenses primarily driven by the completion of the ALTO-203 Phase 2 POC clinical trial; and

Previous wording

General and administrative expenses were $13.9 million for the six months ended June 30, 2026 compared to $11.3 million for the six months ended June 30, 2025. The increase of $2.6 million was primarily due to increases in professional fees.

Current wording

General and administrative expenses were $22.9 million for the nine months ended September 30, 2026 compared to $15.7 million for the nine months ended September 30, 2025. The increase of $7.2 million was primarily due to increases in personnel costs and professional fees.

Previous wording

Other income, net increased $0.9 million in the six months ended June 30, 2026 compared to the six months ended June 30, 2025. The increase was primarily due to $0.7 million of expenses related to debt extinguishment costs ($0.4 million of which was non-cash) for our Amended Term Loan which were incurred during the six months ended June 30, 2025 and did not recur during the six months ended June 30, 2026.

Current wording

September 30, 2025. The increase was also driven by $0.7 million of expenses related to debt extinguishment costs ($0.4 million of which was non-cash) for our Amended Term Loan which were incurred during the nine months ended September 30, 2025 and did not recur during the nine months ended September 30, 2026.

Previous wording

We have incurred net losses and negative cash flows from operations since our inception and anticipate we will continue to incur net losses for the foreseeable future. We have not yet commercialized any of our product candidates, which are in various phases of development, and we do not expect to generate revenue from sales of any of our product candidates for several years, if at all. As we progress through the phases of development, we anticipate that we will incur increasing losses in future quarters and years compared to historical periods. To date, we have funded our operations primarily through the aggregate net proceeds from equity financings (including from our IPO, our October 2025 and March 2026 private placement transactions (described below), our July 2026 Offering, and pre-IPO sales of our convertible preferred stock) and borrowings under our loan and security agreement.

Current wording

We have incurred net losses and negative cash flows from operations since our inception and anticipate we will continue to incur net losses for the foreseeable future. We have not yet commercialized any of our product candidates, which are in various phases of development, and we do not expect to generate revenue from sales of any of our product candidates for several years, if at all. As we progress through the phases of development, we anticipate that we will incur increasing losses in future quarters and years compared to historical periods. To date, we have funded our operations primarily through the aggregate net proceeds from equity financings (including from our IPO, our October 2025 and March 2026 private placement transactions (described below), our July 2026 offering (described below), and pre-IPO sales of our convertible preferred stock) and borrowings under our loan and security agreement.

Previous wording

As of June 30, 2026 and December 31, 2025, we had cash, cash equivalents and restricted cash of $244.2 million and $177.0 million, respectively.

Current wording

As of September 30, 2026 and December 31, 2025, we had cash, cash equivalents and restricted cash of $319.8 million and $177.0 million, respectively.

Previous wording

On July 13, 2026, we entered into an underwriting agreement, or the July 2026 Underwriting Agreement, with BofA Securities, Inc., as representative of the several underwriters set forth therein, collectively referred to as the Underwriters, to issue and sell 3,776,436 shares of our common stock in an underwritten registered direct offering, or the July 2026 Offering, pursuant to our effective shelf registration statement on Form S-3 and a related prospectus and prospectus supplement. The offering price to the public was $26.48 per share of common stock, and the net proceeds to us from the July 2026 Offering were approximately $94.6 million, after deducting underwriting discounts and commissions and estimated net offering expense. The July 2026 Offering closed on July 14, 2026.

Current wording

On July 13, 2026, we entered into an underwriting agreement, or the July 2026 Underwriting Agreement, with BofA Securities, Inc., as representative of the several underwriters set forth therein, collectively referred to as the Underwriters, to issue and sell 3,776,436 shares of our common stock in an underwritten registered direct offering, or the July 2026 Offering, pursuant to our effective shelf registration statement on Form S-3 and a related prospectus and prospectus supplement. The offering price to the public was $26.48 per share of common stock, and the net proceeds to us from the July 2026 Offering were approximately $94.6 million, after deducting underwriting discounts and commissions and net offering expense. The July 2026 Offering closed on July 14, 2026.

Previous wording

As of June 30, 2026 and December 31, 2025, we had an outstanding principal balance of $15.0 million and $16.0 million under the Amended Loan Agreement, respectively.

Current wording

As of September 30, 2026 and December 31, 2025, we had an outstanding principal balance of $12.0 million and $16.0 million under the Amended Loan Agreement, respectively.

Previous wording

Additionally, under the terms of the Amended Loan Agreement, the Lender may, at its option, elect to convert up to $9.0 million of the then outstanding Term Loan ($4.0 million of which was reflected in the Original Loan Agreement and $5.0 million of which is reflected in the Amendment) into shares of our common stock. On November 17, 2025 and March 18, 2026, the Lender elected to convert $4.0 million and $1.0 million, respectively, of its outstanding loan balance into the Company’s common stock. Pursuant to the terms of the Amended Loan Agreement, the conversion price was $4.83 per share, resulting in the issuance of 828,860 and 207,215 shares, respectively. The Lender has the option to convert a remaining $4.0 million into shares of common stock; the conversion price per share for the remaining option is $10.49.

Current wording

Additionally, under the terms of the Amended Loan Agreement, the Lender may, at its option, elect to convert up to $9.0 million of the then outstanding Term Loan ($4.0 million of which was reflected in the Original Loan Agreement and $5.0 million of which is reflected in the Amendment) into shares of our common stock. On November 17, 2025 and March 18, 2026, the Lender elected to convert $4.0 million and $1.0 million, respectively, of its outstanding loan balance into the Company’s common stock. Pursuant to the terms of the Amended Loan Agreement, the conversion price was $4.83 per share, resulting in the issuance of 828,860 and 207,215 shares, respectively. In addition, on September 1, 2026, the Lender elected to convert $3.0 million of its outstanding loan balance into the Company’s common stock. Pursuant to the terms of the Amended Loan Agreement, the conversion price was $10.49 per share, resulting in the issuance of 285,986 shares. As of September 30, 2026, the Lender has the option to convert a remaining $1.0 million of outstanding Term Loan into shares of our common stock at a conversion price of $10.49 per share.

Previous wording

Convertible Grant Agreement provides Wellcome with a limited right to exploit ALTO-100, solely in bipolar depression, subject to a revenue share between Wellcome and us of any proceeds arising from Wellcome’s exploitation. Outstanding amounts under the Convertible Loan accrue interest at an annual rate equal to the Sterling Overnight Index Rate plus 2%, subject to potential adjustment if such interest rate equals or exceeds 9% at any time. At any time after the second anniversary of the effective date of the Convertible Grant Agreement or in connection with an event of default, Wellcome has the right, at its election, to convert some or all of the Convertible Loan into shares of our common stock at a price per share equal to a 20% discount to the thirty-day volume-weighted average price of Common Stock on the New York Stock Exchange at the date of such conversion. The Convertible Grant Agreement provides that in no event shall the aggregate number of shares of our common stock issued pursuant to conversion of the Convertible Loan exceed 5,363,326, which is equal to 19.9% of the number of shares of our common stock outstanding as of the date of the Convertible Grant Agreement. At any time after the fifth anniversary of the date of the Convertible Grant Agreement or in connection with an event of default, Wellcome may require repayment of the Convertible Loan in full, together with accrued interest, to the extent not converted as described above.

Current wording

We may use proceeds from the Convertible Loan solely to advance development of ALTO-100 in bipolar depression. In addition, if we do not exploit or develop ALTO-100 (other than for safety or efficacy concerns) within a specified period following the completion of our Phase 2b clinical trial evaluating ALTO-100 in patients with bipolar depression, the Convertible Grant Agreement provides Wellcome with a limited right to exploit ALTO-100, solely in bipolar depression, subject to a revenue share between Wellcome and us of any proceeds arising from Wellcome’s exploitation. Outstanding amounts under the Convertible Loan accrue interest at an annual rate equal to the Sterling Overnight Index Rate plus 2%, subject to potential adjustment if such interest rate equals or exceeds 9% at any time. At any time after the second anniversary of the effective date of the Convertible Grant Agreement or in connection with an event of default, Wellcome has the right, at its election, to convert some or all of the Convertible Loan into shares of our common stock at a price per share equal to a 20% discount to the thirty-day volume-weighted average price of Common Stock on the New York Stock Exchange at the date of such conversion. The Convertible Grant Agreement provides that in no event shall the aggregate number of shares of our common stock issued pursuant to conversion of the Convertible Loan exceed 5,363,326, which is equal to 19.9% of the number of shares of our common stock outstanding as of the date of the Convertible Grant Agreement. At any time after the fifth anniversary of the date of the Convertible Grant Agreement or in connection with an event of default, Wellcome may require repayment of the Convertible Loan in full, together with accrued interest, to the extent not converted as described above.

Previous wording

Net cash used in operating activities was$46.9 million for the six months ended June 30, 2026, as compared to $30.3 million for the six months ended June 30, 2025. The increase in cash used was the result of an increase in net losses of $21.0 million which was partially offset by increased non-cash stock-based compensation expenses of $2.4 million.

Current wording

Net cash used in operating activities was$67.6 million for the nine months ended September 30, 2026, as compared to $40.3 million for the nine months ended September 30, 2025. The increase in cash used was the result of an increase in net losses of $31.9 million which was partially offset by increased non-cash stock-based compensation expenses of $3.7 million.

Previous wording

Net cash used in investing activities six months ended June 30, 2026 consisted of purchases of property and equipment that are being used for research and development purposes.

Current wording

Net cash used in investing activities nine months ended September 30, 2026 consisted of purchases of property and equipment that are being used for research and development purposes.

Previous wording

The net cash used in investing activities for the six months ended June 30, 2025 was negligible.

Current wording

The net cash used in investing activities for the nine months ended September 30, 2025 was negligible.

Previous wording

Net cash provided by financing activities was $114.7 million for the six months ended June 30, 2026, primarily related to the proceeds from our 2026 PIPE Purchase Agreement.

Current wording

Net cash provided by financing activities was $211.0 million for the nine months ended September 30, 2026, primarily related to the proceeds from our 2026 PIPE Purchase Agreement and the July 2026 Offering.

Previous wording

Net cash provided by financing activities was$9.7 million for thesix months ended June 30, 2025, primarily related to borrowings under our Amended Loan Agreement as well as the drawdown of$0.8 million under our Convertible Grant Agreement.

Current wording

Net cash provided by financing activities was$9.9 million for thenine months ended September 30, 2025, primarily related to borrowings under our Amended Loan Agreement.

Previous wording

We believe that our existing cash and cash equivalents of $243.7 million as of June 30, 2026, together with both the net proceeds of approximately $94.6 million from the July 2026 Offering and the anticipated proceeds under our Convertible Grant Agreement with Wellcome, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 12 months. However, our forecast of the period of time through which our financial resources will be adequate to support our operations is a forward-looking statement that involves risks and uncertainties, and actual results could vary materially. We have based this estimate on assumptions that may prove to be wrong, and we could expend our capital resources sooner than we currently expect.

Current wording

We believe that our existing cash and cash equivalents of $319.3 million as of September 30, 2026, together with the anticipated proceeds under our Convertible Grant Agreement with Wellcome, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 12 months. However, our forecast of the period of time through which our financial resources will be adequate to support our operations is a forward-looking statement that involves risks and uncertainties, and actual results could vary materially. We have based this estimate on assumptions that may prove to be wrong, and we could expend our capital resources sooner than we currently expect.

Previous wording

In addition to ongoing needs to fund our operations, our material cash requirements as of June 30, 2026 consist primarily of obligations under both our Amended Loan Agreement (see Note 4 to our unaudited condensed consolidated financial statements included elsewhere in this Quarterly Report) and our lease commitment for our headquarters office space located in Mountain View, California with an initial lease term of 65 months that terminates in March 2030 for which we currently have a $5.6 million commitment remaining. If the Company elects to terminate the lease after the third lease year, including payments already made, the Company will make payments of approximately $4.0 million over the term of the lease.

Current wording

In addition to ongoing needs to fund our operations, our material cash requirements as of September 30, 2026 consist primarily of obligations under both our Amended Loan Agreement (see Note 4 to our unaudited condensed consolidated financial statements included elsewhere in this Quarterly Report) and our lease commitment for our headquarters office space located in Mountain View, California with an initial lease term of 65 months. On September 21, 2026, the Company exercised its early termination right to terminate the lease as of October 31, 2027, or the Early Termination Date. As of the Early Termination Date, including payments already made, the Company will make payments of approximately $4.0 million over the term of the lease.

Previous wording

On May 31, 2025, we entered into an asset purchase agreement, or Chase Agreement, with Chase Therapeutics Corporation, or Chase, to acquire all patent, know-how and other rights to ALTO-207, ALTO-208, and certain related assets. In May 2026, we achieved aclinical milestone under the Chase Agreement related to the initiation of our Phase 2b clinical trial evaluating ALTO-207 and paid $2.0 million to Chase during the three and six months ended June 30, 2026.

Current wording

On May 31, 2025, we entered into an asset purchase agreement, or Chase Agreement, with Chase Therapeutics Corporation, or Chase, to acquire all patent, know-how and other rights to ALTO-207, ALTO-208, and certain related assets. In May 2026, we achieved aclinical milestone under the Chase Agreement related to the initiation of our Phase 2b clinical trial evaluating ALTO-207 and paid $2.0 million to Chase during thenine months ended September 30, 2026.