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During the course of your relationship with Alto Neuroscience, Inc. (“Alto”), you may receive material information that is not yet publicly available (“material nonpublic information”) about Alto or other publicly traded companies. Material nonpublic information may give you, or someone you pass that information on to, a leg up over others when deciding whether to buy, sell, or otherwise transact in Alto’s securities or the securities of another publicly traded company. This policy sets forth guidelines with respect to transactions in Alto securities and in the securities of other applicable publicly traded companies, in each case by our employees, directors, and consultants and the other persons or entities subject to this policy as described below.

•disclose material nonpublic information to persons within Alto whose jobs do not require them to have that information, or outside of Alto to other persons, such as family, friends, business associates, and investors, unless the disclosure is made in accordance with Alto’s policies regarding the protection or authorized external disclosure of information regarding Alto; or

The prohibition against insider trading is absolute. It applies even if the decision to trade is not based on such material nonpublic information. It also applies to transactions that may be necessary or justifiable for independent reasons (such as the need to raise money for an emergency expenditure) and also to very small transactions. All that matters is whether you are aware of any material nonpublic information relating to Alto at the time of the transaction.

The U.S. federal securities laws do not recognize any mitigating circumstances to insider trading. In addition, even the appearance of an improper transaction must be avoided to preserve Alto’s reputation for adhering to the highest standards of conduct. In some circumstances, you may need to forgo a planned transaction even if you planned it before becoming aware of the material nonpublic information. So, even if you believe you may suffer an economic loss or sacrifice an anticipated profit by waiting to trade, you must wait.

It is also important to note that the laws prohibiting insider trading are not limited to trading by the insider alone; advising others to trade on the basis of material nonpublic information is illegal and squarely prohibited by this policy. Liability in such cases can extend both to the “tippee”—the person to whom the insider disclosed material nonpublic information—and to the “tipper,” the insider himself or herself. In such cases, you can be held liable for your own transactions, as well as the transactions by a tippee and even the transactions of a tippee’s tippee. For these and other reasons, it is the policy of Alto that no employee, director, or consultant of Alto (or any other person or entity subject to this policy) may either (a) recommend to another person or entity that they buy, hold, or sell Alto’s securities at any time, or (b) disclose material nonpublic information to persons within Alto whose jobs do not require them to have that information, or outside of Alto to other persons (unless the disclosure is made in accordance with Alto’s policies regarding the protection or authorized external disclosure of information regarding Alto).

In addition, it is the policy of Alto that no person subject to this policy who, in the course of his or her relationship with Alto, learns of any confidential information that is material to another publicly traded company with which Alto does business, including a partner or collaborator of Alto, may trade in that other company’s securities until the information becomes public or is no longer material to that other company.

This policy applies to all transactions in securities issued by Alto, as well as derivative securities that are not issued by Alto, such as exchange-traded put or call options or swaps relating to Alto’s securities. Accordingly, for purposes of this policy, the terms “trade,” “trading,” and “transactions” include not only purchases and sales of Alto’s common stock in the public market but also any other purchases, sales, transfers, gifts, or other acquisitions and dispositions of common or preferred equity, options, warrants, and other securities (including debt securities) and other arrangements or transactions that affect economic exposure to changes in the prices of these securities.

This policy applies to you and all other employees, directors, and consultants of Alto and its subsidiaries. This policy also applies to members of your family who reside with you, any other persons with whom you share a household, any family members who do not live in your household but whose transactions in Alto’s securities are directed by you or are subject to your influence or control, and any other individuals or entities whose transactions in securities you influence, direct, or control (including, e.g., a venture or other investment fund, if you influence, direct or control transactions by the fund). The foregoing persons who are deemed subject to this policy are referred to in this policy as “Related Persons.” You are responsible for making sure that your Related Persons comply with this policy.

It is not always easy to figure out whether you are aware of material nonpublic information. But there is one important factor to determine whether nonpublic information you know about a public company is material: whether the information could be expected to affect the market price of that company’s securities or to be considered important by investors who are considering trading that company’s securities. If the information makes you want to trade, it would probably have the same effect on others. Keep in mind that both positive and negative information can be material.

There is no bright-line standard for assessing materiality; rather, materiality is based on an assessment of all of the facts and circumstances, and is often evaluated by relevant enforcement authorities with the benefit of hindsight. Depending on the specific details, the following items may be considered material nonpublic information until publicly disclosed within the meaning of this policy. There may be other types of information that would qualify as material information as well; use this list merely as a non-exhaustive guide:

The prohibition on trading when you have material nonpublic information lifts once that information becomes publicly disseminated as further described in this paragraph. For information to be considered publicly disseminated, it must be widely disseminated through a press release, a filing with the Securities and Exchange Commission (the “SEC”), or other widely disseminated announcement. Once information is publicly disseminated, it is still necessary to afford the investing public with sufficient time to absorb the information. Generally speaking, information will be considered publicly disseminated for purposes of this policy only after two full trading days have elapsed since the information was publicly disclosed. For example, if we announce material nonpublic information before trading begins on Wednesday, then you may execute a transaction in our securities on Friday; if we announce material nonpublic information after trading ends on Wednesday, then you may execute a transaction in our securities on Monday (in each case subject to any pre-clearance requirements set forth under the heading “Pre-Clearance and Advance Notice of Transactions” below). Depending on the particular circumstances, Alto may determine that a longer or shorter waiting period should apply to the release of specific material nonpublic information.

No directors, officers, other employees, or consultants may engage in any transaction in, or enter into, modify or terminate any contract, instruction, or written plan or arrangement in, Alto’s securities without first notifying and seeking approval from the Company’s Chief Financial Officer or General Counsel or one of their respective designees (each, a “Clearing Officer”) at least two business days in advance of the proposed transaction. The Clearing Officer will then determine whether the transaction may proceed and, if so, will direct the Compliance Officer (as identified in Alto’s Section 16 Compliance Program) to help comply with any required reporting requirements under Section 16(a) of the Exchange Act. Pre-cleared transactions not completed within five business days will require new pre-clearance. Alto may, at its discretion, shorten such period of time.

Advance notice of plans to exercise an outstanding stock option shall be given to the Clearing Officer. Once any transaction takes place, the director or Section 16 officer must immediately notify the Compliance Officer and any other individuals identified under the heading “Notification of Execution of Transaction” in Alto’s Section 16 Compliance Program so that Alto may assist in any Section 16 reporting obligations.

From time to time, an event may occur that is material to Alto and is known by only a few directors, officers, and/or employees. So long as the event remains material and nonpublic, the persons designated by the Chief Executive Officer, Chief Financial Officer, or General Counsel may not trade in Alto’s securities. In that situation, Alto will notify the designated individuals that neither they nor their Related Persons may trade in Alto’s securities. The existence of an event-specific trading blackout should also be considered material nonpublic information and should not be communicated to any other person. Even if you have not been designated as a person who should

1.Option Exercises. This policy does not apply to the exercise of options granted under Alto’s equity compensation plans for cash or, where permitted under the option, by a net exercise transaction with the Company or by delivery to Alto of already-owned Alto stock. This policy does, however, apply to any sale of stock as part of a broker-assisted cashless exercise or any other market sale, whether or not for the purpose of generating the cash needed to pay the exercise price or pay taxes.

2.Tax Withholding Transactions. This policy does not apply to the surrender of shares directly to Alto to satisfy tax withholding obligations as a result of the issuance of shares upon vesting or exercise of restricted stock units, options, or other equity awards granted under Alto’s equity compensation plans. Of course, any market sale of the stock received upon exercise or vesting of any such equity awards remains subject to all provisions of this policy whether or not for the purpose of generating the cash needed to pay the exercise price or pay taxes.

3.ESPP. This policy does not apply to the purchase of stock by employees under Alto’s Employee Stock Purchase Plan (“ESPP”) on periodic designated dates in accordance with the ESPP. This policy does, however, apply to any sale of stock acquired pursuant to the ESPP.

4.10b5-1 Automatic Trading Programs. Under Rule 10b5-1 of the Securities Exchange Act of 1934, as amended (“Exchange Act”), and as permitted by Alto, employees, directors, and executive officers may establish a trading plan under which a broker is instructed to buy and sell Alto securities based on pre-determined criteria (a “10b5-1 Trading Plan”). So long as a 10b5-1 Trading Plan is properly established, purchases and sales of Alto securities pursuant to that 10b5-1 Trading Plan are not subject to this policy. To be properly established, an employee’s, director’s, or executive officer’s 10b5-1 Trading Plan must be established in compliance with the requirements of Rule 10b5-1 of the Exchange Act and any applicable 10b5-1 trading plan guidelines of Alto at a time when Alto was not in a trading blackout period and they were not otherwise aware of any material nonpublic information relating to Alto or the securities subject to the 10b5-1 Trading Plan. Moreover, all 10b5-1 Trading Plans must be reviewed and approved by Alto before being established to confirm that the 10b5-1 Trading Plan complies with all pertinent company policies and applicable securities laws.

2.Hedging Transactions. Hedging or monetization transactions can be accomplished through a number of possible mechanisms, including through the use of financial instruments such as prepaid variable forwards, equity swaps, collars, and exchange funds. Such hedging transactions may permit an Alto employee, director, or consultant to continue to own Alto’s securities obtained through employee benefit plans or otherwise, but without the full risks and rewards of ownership. When that occurs, the Alto employee, director, or consultant may no longer have the same objectives as Alto’s other stockholders. Therefore, Alto employees, directors, and consultants are prohibited from engaging in any such transactions.

3.Margin Accounts and Pledged Securities. Securities held in a margin account as collateral for a margin loan may be sold by the broker without the customer’s consent if the customer fails to meet a margin call. Similarly, securities pledged (or hypothecated) as collateral for a loan may be sold in foreclosure if the borrower defaults on the loan. Because a margin sale or foreclosure sale may occur at a time when the pledgor is aware of material nonpublic information or otherwise is not permitted to trade in Alto’s securities, Alto employees, directors, and consultants are prohibited from holding Alto’s securities in a margin account or otherwise pledging Alto’s securities as collateral for a loan.

4.Standing and Limit Orders. Standing and limit orders (except standing and limit orders under approved 10b5-1 Trading Plans, as discussed above) create heightened risks for insider trading violations similar to the use of margin accounts. There is no control over the timing of purchases or sales that result from standing instructions to a broker, and as a result the broker could execute a transaction when an Alto employee, director, or consultant is in possession of material nonpublic information. Alto therefore discourages placing standing or limit orders on Alto’s securities. If a person subject to this policy determines that they must use a standing order or limit order (other than under an approved 10b5-1 Trading Plan as discussed above), the order should be limited to short duration and the person using such standing order or limit order is required to cancel such instructions immediately in the event restrictions are imposed on their ability to trade pursuant to this policy.

Officers and directors subject to the reporting obligations under Section 16 of the Exchange Act should take care to avoid short-swing transactions (within the meaning of Section 16(b) of the Exchange Act) and the restrictions on sales by control persons (Rule 144 under the Securities Act of 1933, as amended), and should file all appropriate Section 16(a) reports (Forms 3, 4, and 5), which are described in Alto’s Section 16 Compliance Program, and any notices of sale required by Rule 144.

This policy continues to apply to your transactions in Alto’s securities and the securities of other applicable public companies as more specifically set forth in this policy, even after your relationship with Alto has ended. If you are aware of material nonpublic information when your

relationship with Alto ends, you may not trade Alto’s securities or the securities of other applicable publicly traded companies until the material nonpublic information has been publicly disseminated or is no longer material. Further, if you leave Alto during a trading blackout period, then you may not trade Alto’s securities or the securities of other applicable companies until the trading blackout period has ended.

Persons subject to this policy have ethical and legal obligations to maintain the confidentiality of information about Alto and to not engage in transactions in Alto’s securities or the securities of other applicable public companies while aware of material nonpublic information, as more specifically set forth in this policy. Each individual is responsible for making sure that he or she complies with this policy, and that any family member, household member, or other person or entity whose transactions are subject to this policy, as discussed under the heading “Persons Subject to this Policy” above, also comply with this policy. In all cases, the responsibility for determining whether an individual is aware of material nonpublic information rests with that individual, and any action on the part of Alto or any employee or director of Alto pursuant to this policy (or otherwise) does not in any way constitute legal advice or insulate an individual from liability under applicable securities laws. You could be subject to severe legal penalties and disciplinary action by Alto for any conduct prohibited by this policy or applicable securities laws. See “Penalties” below.

Anyone who engages in insider trading or otherwise violates this policy may be subject to both civil liability and criminal penalties. Violators also risk disciplinary action by Alto, including termination of employment. Anyone who has questions about this policy should contact their own attorney or Alto’s General Counsel, at generalcounsel@altoneuroscience.com. Please also see Frequently Asked Questions, which are attached as Exhibit A.

Alto is committed to continuously reviewing and updating its policies and procedures. Alto therefore reserves the right to amend, alter or terminate this policy at any time and for any reason. A current copy of Alto’s policies regarding insider trading are posted on our website at www.altoneuroscience.com.

A: Generally speaking, insider trading is the buying or selling of stocks, bonds, futures, or other securities by someone who possesses or is otherwise aware of material nonpublic information about the securities or the issuer of the securities. Insider trading also includes trading in derivatives (such as put or call options) where the price is linked to the underlying price of a company’s stock. It does not matter whether the decision to buy or sell was influenced by the material nonpublic information, how many shares you buy or sell, or whether it has an effect on the stock price. Bottom line: If, during the course of your relationship with Alto, you become aware of material nonpublic information about Alto and you trade in Alto’s securities, you have broken the law and violated our insider trading policy. In addition, our insider trading policy provides that if in the course of your relationship with Alto, you learn of any confidential information that is material to another publicly traded company with which Alto does business, including partner or collaborator of Alto, you may not trade in that other company’s securities until the information becomes public or is no longer material to that other company.

A: If company insiders are able to use their confidential knowledge to their financial advantage, other investors would not have confidence in the fairness and integrity of the market. This ensures that there is an even playing field by requiring those who are aware of material nonpublic information to refrain from trading.

A: Information is material if it would influence a reasonable investor to buy or sell a stock, bond future or other security. This could mean many things: financial results, clinical or regulatory results, potential acquisitions, or major contracts to name just a few. Information is nonpublic if it has not yet been publicly disseminated within the meaning of our insider trading policy.

A: Anyone who buys or sells a security while aware of material nonpublic information, or provides material nonpublic information that someone else uses to buy or sell a security, may be guilty of insider trading. This applies to all individuals, including officers, directors, and others who do not even work at Alto. Regardless of who you are, if you know something material about the value of a security that not everyone knows and you trade (or convince someone else to trade) in that security, you may be found guilty of insider trading.

A: The same rules apply to U.S. and foreign employees and consultants. The Securities and Exchange Commission (the U.S. government agency in charge of investor protection) and the Financial Industry Regulatory Authority (a private regulator that oversees U.S. securities exchanges) routinely investigate trading in a company’s securities conducted by individuals and firms based abroad. In addition, as an Alto director, employee, or consultant, our policies apply to you no matter where you work.

A: That is called “tipping.” You are the “tipper” and the other person is called the “tippee.” If the tippee buys or sells based on that material nonpublic information, both you and the “tippee” could be found guilty of insider trading. In fact, if you tell family members who tell others and those people then trade on the information, those family members and the “tippee” might be found guilty of insider trading too. To prevent this, you may not discuss material nonpublic information about the company with anyone outside Alto, including spouses, family members, friends, or business associates (unless the disclosure is made in accordance with Alto’s policies regarding the protection or authorized external disclosure of information regarding Alto). This includes anonymous discussions on the internet about Alto or companies with which Alto does business.

A: That is still tipping, and you can still be responsible for insider trading. You may never recommend to another person that they buy, hold, or sell Alto’s common stock or any derivative security related to Alto’s common stock, since that could be a form of tipping.

A: In addition to disciplinary action by Alto—which may include termination of employment—you may be liable for civil sanctions for trading on material nonpublic information. The sanctions may include return of any profit made or loss avoided as well as penalties of up to three times any profit made or any loss avoided. Persons found liable for tipping material nonpublic information, even if they did not trade themselves, may be liable for the amount of any profit gained or loss avoided by everyone in the chain of tippees as well as a penalty of up to three times that amount. In addition, anyone convicted of criminal insider trading could face prison and additional fines.

A: Yes, you may be restricted from doing so due to your awareness of material nonpublic information. U.S. insider trading laws generally restrict everyone aware of material nonpublic information about a company from trading in that company’s securities, regardless of whether the person is directly connected with that company, except in limited circumstances. You should be particularly conscious of this restriction if, through your position at Alto, you sometimes obtain sensitive, material information about other companies and their business dealings with Alto. Please also refer to Question 1 above and our insider trading policy with respect to restrictions on trading in the securities of other public companies.

A: Not necessarily. Even if you do not violate U.S. law, you may still violate our policies. For example, employees and consultants may violate our policies by breaching their confidentiality obligations or by recommending Alto stock as an investment, even if these actions do not violate securities laws. Our policies are stricter than the law requires so that we and our employees and consultants can avoid even the appearance of wrongdoing. Therefore, please review the entire policy carefully.

A: If you are aware of material nonpublic information, you may not buy or sell our common stock until two full trading days have elapsed since the information was publicly disclosed. At that point, the information is considered publicly disseminated for purposes of our insider trading policy. For example, if we announce material nonpublic information before trading begins on Wednesday, then you may execute a transaction in our securities on Friday; if we announce material nonpublic information after trading ends on Wednesday, then you may execute a transaction in our securities on Monday (in each case subject to any pre-clearance requirements set forth in this policy). Even if you are not aware of any material nonpublic information, you may not trade our common stock during any trading “blackout” period. And finally, all directors, officers, other employees, and consultants must pre-clear any purchases or sales of stock with the Clearing Officer two business days in advance of the proposed transaction as set forth under the heading “Pre-Clearance and Advance Notice of Transactions” of this policy.

A: No, unless it is in connection with a 10b5-1 Trading Plan (see Question 27 below). If you have any open orders when a blackout period commences other than in connection with a 10b5-1 Trading Plan, it is your responsibility to cancel these orders with your broker. If you have an open order and it executes after a blackout period commences not in connection with a 10b5-1 Trading

“Derivative securities” are securities other than common stock that are speculative in nature because they permit a person to leverage their investment using a relatively small amount of money. Examples of derivative securities include “put options” and “call options.” These are different from employee options and other equity awards granted under our equity compensation plans, which are not derivative securities for purposes of our policy.

“Short selling” is profiting when you expect the price of the stock to decline, and includes transactions in which you borrow stock from a broker, sell it, and eventually buy it back on the market to return the borrowed shares to the broker. Profit is realized if the stock price decreases during the period of borrowing.

A: Many companies with volatile stock prices have adopted similar policies because of the temptation it represents to try to benefit from a relatively low-cost method of trading on short-term swings in stock prices, without actually holding the underlying common stock, and encourages speculative trading. We are dedicated to building stockholder value, short selling our common stock conflicts with our values and would not be well-received by our stockholders.

A: Margin loans are subject to a margin call whether or not you possess material nonpublic information at the time of the call. If a margin call were to be made at a time when you were aware of material nonpublic information and you could not or did not supply other collateral, you may be liable under insider trading laws because of the sale of the securities (through the margin call). The sale would be attributed to you even though the lender made the ultimate determination to sell. The

A: No. Pledging your shares as collateral for a personal loan could cause the pledgee to transfer your shares during a trading blackout period or when you are otherwise aware of material nonpublic information. As a result, you may not pledge your shares as collateral for a loan.

A: Hedging or monetization transactions, including through the use of financial instruments such as prepaid variable forwards, equity swaps, collars, and exchange funds are prohibited by our insider trading policy. Since such hedging transactions allow you to continue to own Alto’s securities obtained through employee benefit plans or otherwise, but without the full risks and rewards of ownership, you may no longer have the same objectives as Alto’s other shareholders. Therefore, our insider trading policy prohibits you from engaging in any such transactions.

A: Yes. You may exercise the options for cash (or via net exercise transaction with the company) and receive shares, but you may not sell the shares (even to pay the exercise price or any taxes due) during a trading blackout period or any time that you are aware of material nonpublic information. To be clear, you may not effect a broker-assisted cashless exercise (these cashless exercise transactions include a market sale) during a trading blackout period or any time that you are aware of material nonpublic information

A: It depends. If your employment with Alto ends during a trading blackout period, you will be subject to the remainder of that trading blackout period. If your employment with Alto ends on a day that the trading window is open, you will not be subject to the next trading blackout period. However, even if you are not subject to our trading blackout period after you leave Alto, you should not trade in Alto securities if you are aware of material nonpublic information. That restriction stays with you as long as the information you possess is material and not publicly disseminated within the meaning of our insider trading policy.

A: Yes, subject to the requirements discussed in our insider trading policy and any 10b5-1 trading plan guidelines. A routine trading program, also known as a 10b5-1 plan, allows you to set up a highly structured program with your stock broker where you specify ahead of time the date, price, and amount of securities to be traded. If you wish to create a 10b5-1 plan, please contact our legal team for approval at generalcounsel@altoneuroscience.com.