Skip to main
  2. Stocks
  3. Quantum-Si
  4. After-Market
QSI

Quantum-Si (QSI) After-Hours

DateAfter-hours PriceAfter-hours HighAfter-hours Low
$1.21$1.25$1.20

Quantum-Si (QSI) After-Hours Trading Summary

As of on , Quantum-Si (QSI) is trading at $1.21 in the after-hours session, down -$0.38 (-23.75%) from the regular market close of $1.59.

During after-hours trading, Quantum-Si (QSI) stock has ranged between $1.25 and $1.20, with the most recent trade recorded at $1.21.

24/5 trading

How to Buy or Trade Quantum-Si (QSI) After Market Close

Looking to trade Quantum-Si stock (QSI) after the market closes? Public offers 24/5 trading from Sunday at 8:00 PM ET through Friday at 8:00 PM ET, including after-hours and overnight trading. Keep in mind that extended-hours trading may involve lower liquidity and wider bid-ask spreads than normal sessions. Follow the steps below to get started.

  1. 1

    Create a Public brokerage account

    Sign up for a free brokerage account with Public. You can open an account directly on the website or by downloading the Public app for iOS or Android.

  2. 2

    Deposit funds into your account

    Add funds to your Public account by linking a bank account, using a debit card, or initiating a wire transfer, so you’re ready to invest during extended hours.

  3. 3

    Find Quantum-Si (QSI) stock and place your after-hours order

    Go to the Explore tab and type “Quantum-Si” or “QSI” into the search bar. Select the stock from the results to view its quote page. From there, you can enter the amount you’d like to invest and place an after-hours order directly.

  4. 4

    Track your Quantum-Si (QSI) shares in your portfolio

    Once your order is executed, Quantum-Si (QSI) will appear in your portfolio. You can track your QSI shares alongside other assets—including stocks, ETFs, crypto, bonds, options, and your high-yield cash account—all in one place on Public.

Quantum-Si (QSI) After-Hours Price History

Date
$1.22$1.21-0.63%
$1.27$1.30+2.27%
$1.22$1.20-1.57%
$1.29$1.30+0.78%
$1.55$1.49-3.87%
View all

FAQs About Quantum-Si (QSI) After hours

As of 8:00 PM ET Oct 9, 2026, Quantum-Si (QSI) is trading at $1.21 in the after-hours session, down -$0.38 (-23.75%) from the regular market close of $1.59. After-hours prices reflect trading activity that occurs after the market closes at 4:00 PM ET.

Quantum-Si (QSI) is currently trading down in the after-hours session, with a price of $1.21, which is -$0.38 (-23.75%) lower than the regular close of $1.59. After-hours movement shows how the stock is performing outside of normal trading hours.

In the latest after-hours session, Quantum-Si (QSI) has traded between a low of $1.20 and a high of $1.25. These prices reflect extended-hours activity after the regular session ends.

After-hours trading for Quantum-Si (QSI) runs from 4:00 PM to 8:00 PM ET. On Public, eligible stocks can continue trading overnight as part of 24/5 trading, available from Sunday at 8:00 PM ET through Friday at 8:00 PM ET.

You can trade Quantum-Si (QSI) after hours through brokerages that offer extended-hours trading, including Public. Public offers 24/5 trading for eligible stocks from Sunday at 8:00 PM ET through Friday at 8:00 PM ET. Get started with a Public brokerage account to trade QSI.

Quantum-Si (QSI)

Volume: 26.13M

Order type

Buy in

Order amount

Est. shares

0 shares

Sign up to buy
Disclaimer: Any investment listed here, which may be available on the Public platform, is intended to be used for informational purposes only, should not be the sole basis for making an investment decision, and is not a recommendation or advice.

© Copyright 2026 Public Holdings, Inc. All Rights Reserved.

Market data powered by Xignite.

All investments involve the risk of loss and the past performance of a security or a financial product does not guarantee future results or returns. You should consult your legal, tax, or financial advisors before making any financial decisions. This material is not intended as a recommendation, offer, or solicitation to purchase or sell securities, open a brokerage account, or engage in any investment strategy.

Stocks, ETFs, Options, Bonds.
Self-directed brokerage accounts and brokerage services for US-listed, registered securities, options, and Bonds, except for treasury securities offered through Jiko Securities, Inc., are offered to self-directed customers by Open to the Public Investing, Inc. (“Public Investing”), a registered broker-dealer and member of FINRA & SIPC. Additional information about your broker can be found by clicking here. Public Investing is a wholly-owned subsidiary of Public Holdings, Inc. (“Public Holdings”). This is not an offer, solicitation of an offer, or advice to buy or sell securities or open a brokerage account in any jurisdiction where Public Investing is not registered. Securities products offered by Public Investing are not FDIC insured. Apex Clearing Corporation, our clearing firm, has additional insurance coverage in excess of the regular SIPC limits. Additional information can be found here.

Options.
Certain requirements must be met in order to trade options. Options can be risky and are not suitable for all investors. Options transactions are often complex, and investors can rapidly lose the entire amount of their investment or more in a short period of time. Investors should consider their investment objectives and risks carefully before investing in options. Refer to the Characteristics and Risks of Standardized Options before considering any options transaction. Supporting documentation for any claims, if applicable, will be furnished upon request. Tax considerations with options transactions are unique and investors considering options should consult their tax advisor as to how taxes affect the outcome of each options strategy.

Options Order Flow Rebates.
If you are enrolled in our Options Order Flow Rebate Program, Public Investing will share a percentage of our estimated order flow revenue for each completed options trade as a rebate to help reduce your trading costs. Rebate rates vary monthly from $0.06-$0.18 and depend on your current and prior month’s options trading volume. This rebate will be deducted from your cost to place the trade and will be reflected on your trade confirmation. To learn more, see our Options Rebate Program Terms & Conditions, Order Rebate FAQ and Fee Schedule.

Bonds.
“Bonds” shall refer to corporate debt securities and U.S. government securities offered on the Public platform through a self-directed brokerage account held at Public Investing and custodied at Apex Clearing. For purposes of this section, Bonds exclude treasury securities held in treasury accounts with Jiko Securities, Inc. as explained under the “ Treasury Accounts” section.

Investments in Bonds are subject to various risks including risks related to interest rates, credit quality, market valuations, liquidity, prepayments, early redemption, corporate events, tax ramifications and other factors. The value of Bonds fluctuate and any investments sold prior to maturity may result in gain or loss of principal. In general, when interest rates go up, Bond prices typically drop, and vice versa. Bonds with higher yields or offered by issuers with lower credit ratings generally carry a higher degree of risk. All fixed income securities are subject to price change and availability, and yield is subject to change. Bond ratings, if provided, are third party opinions on the overall bond's credit worthiness at the time the rating is assigned. Ratings are not recommendations to purchase, hold, or sell securities, and they do not address the market value of securities or their suitability for investment purposes.

A Bond Account is a self-directed brokerage account with Public Investing. Deposits into this account are used to purchase 10 investment-grade and high-yield bonds. The Bond Account’s yield is the average, annualized yield to worst (YTW) across all ten bonds in the Bond Account, before fees. A bond’s yield is a function of its market price, which can fluctuate; therefore a bond’s YTW is not “locked in” until the bond is purchased, and your yield at time of purchase may be different from the yield shown here. The “locked in” YTW is not guaranteed; you may receive less than the YTW of the bonds in the Bond Account if you sell any of the bonds before maturity or if the issuer defaults on the bond. Public Investing charges a markup on each bond trade. See our Fee Schedule.

Bond Accounts are not recommendations of individual bonds or default allocations. The bonds in the Bond Account have not been selected based on your needs or risk profile. You should evaluate each bond before investing in a Bond Account. The bonds in your Bond Account will not be rebalanced and allocations will not be updated, except for Corporate Actions.

Fractional Bonds also carry additional risks including that they are only available on Public and cannot be transferred to other brokerages. Read more about the risks associated with fixed income and fractional bonds. See Bond Account Disclosures to learn more.

High-Yield Cash Account.
A High-Yield Cash Account is a secondary brokerage account with Public Investing. Funds in your High-Yield Cash Account are automatically deposited into partner banks (“Partner Banks”), where that cash earns interest and is eligible for FDIC insurance. See here for a list of current Partner Banks. Your Annual Percentage Yield is variable and may change at the discretion of the Partner Banks or Public Investing. Apex Clearing and Public Investing receive administrative fees for operating this program, which reduce the amount of interest paid on swept cash. Neither Public Investing nor any of its affiliates is a bank. Learn more.

Cryptocurrency.
Cryptocurrency trading, execution and custody services are provided by Zero Hash LLC (“Zero Hash”). Zero Hash is licensed to engage in a virtual currency business by the New York State Department of Financial Services, and is a licensed money transmitter in all other US states and certain US territories. Zero Hash is not a registered broker-dealer or a member of FINRA. Cryptocurrencies are not stocks and your cryptocurrency investments are not FDIC insured or SIPC protected.

Cryptocurrency investing is highly speculative, involves a high degree of risk, and has the potential for loss of the entire amount of an investment. Cryptocurrencies offered by Zero Hash are not securities and are not FDIC insured or protected by SIPC. Your cryptocurrency assets are held by Zero Hash, not Public. Your Zero Hash Crypto account is separate from your brokerage account with Public Investing, which holds US-listed stocks and ETFs. Please review the Risk Disclosures before trading.

Treasury Accounts.
Investing services in treasury accounts offering 6 month US Treasury Bills on the Public platform are through Jiko Securities, Inc. (“JSI”), a registered broker-dealer and member of FINRA & SIPC. See JSI’s FINRA BrokerCheck and Form CRS for further information. JSI uses funds from your Treasury Account to purchase T-bills in increments of $100 “par value” (the T-bill’s value at maturity). T-bills are purchased at a discount to the par value and the T-bill’s yield represents the difference in price between the “par value” and the “discount price.” Aggregate funds in your Treasury Account in excess of the T-bill purchases will remain in your Treasury Account as cash. The value of T-bills fluctuate and investors may receive more or less than their original investments if sold prior to maturity. T-bills are subject to price change and availability - yield is subject to change. Past performance is not indicative of future performance. Investments in T-bills involve a variety of risks, including credit risk, interest rate risk, and liquidity risk. As a general rule, the price of a T-bills moves inversely to changes in interest rates. Although T-bills are considered safer than many other financial instruments, you could lose all or a part of your investment. See Jiko U.S. Treasuries Risk Disclosures for further details.

Investments in T-bills: Not FDIC Insured; No Bank Guarantee; May Lose Value.

Banking services and bank accounts are offered by Jiko Bank, a division of Mid-Central National Bank. JSI and Jiko Bank are not affiliated with Public Holdings, Inc. (“Public”) or any of its subsidiaries. None of these entities provide legal, tax, or accounting advice. You should consult your legal, tax, or financial advisors before making any financial decisions. This material is not intended as a recommendation, offer, or solicitation to purchase or sell securities, open a brokerage account, or engage in any investment strategy.

Commission-free trading refers to $0 commissions charged on trades of US listed registered securities placed during the US Markets Regular Trading Hours in self-directed brokerage accounts offered by Public Investing. Keep in mind that other fees such as regulatory fees, Premium subscription fees, commissions on trades during extended trading hours, wire transfer fees, and paper statement fees may apply to your brokerage account. Please see Public’s Investing’s Fee Schedule to learn more.

Fractional shares are illiquid outside of Public and not transferable. For a complete explanation of conditions, restrictions and limitations associated with fractional shares, see our Fractional Share Disclosure to learn more.

Investment Plans. Investment Plans (“Plans”) shown in our marketplace are for informational purposes only and are meant as helpful starting points as you discover, research and create a Plan that meets your specific investing needs. Plans are self-directed purchases of individually-selected assets, which may include stocks, ETFs and cryptocurrency. Plans are not recommendations of a Plan overall or its individual holdings or default allocations. Plans are created using defined, objective criteria based on generally accepted investment theory; they are not based on your needs or risk profile. You are responsible for establishing and maintaining allocations among assets within your Plan. Plans involve continuous investments, regardless of market conditions. Diversification does not eliminate risk. See our Investment Plans Terms and Conditions and Sponsored Content and Conflicts of Interest Disclosure.

Alpha.
Alpha is an experiment brought to you by Public Holdings, Inc. (“Public”). Alpha is an AI research tool powered by GPT-4, a generative large language model. Alpha is experimental technology and may give inaccurate or inappropriate responses. Output from Alpha should not be construed as investment research or recommendations, and should not serve as the basis for any investment decision. All Alpha output is provided “as is.” Public makes no representations or warranties with respect to the accuracy, completeness, quality, timeliness, or any other characteristic of such output. Your use of Alpha output is at your sole risk. Please independently evaluate and verify the accuracy of any such output for your own use case.

Market Data.
Quotes and other market data for Public’s product offerings are obtained from third party sources believed to be reliable, but Public makes no representation or warranty regarding the quality, accuracy, timeliness, and/or completeness of this information. Such information is time sensitive and subject to change based on market conditions and other factors. You assume full responsibility for any trading decisions you make based upon the market data provided, and Public is not liable for any loss caused directly or indirectly by your use of such information. Market data is provided solely for informational and/or educational purposes only. It is not intended as a recommendation and does not represent a solicitation or an offer to buy or sell any particular security.

View Full Disclosures