Alphabet files 424B5: prospectus (424B)

The information contained in this preliminary prospectus supplement and the accompanying prospectus is not complete and may be changed.

This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell the notes and are not soliciting an offer to buy the notes in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED NOVEMBER 2, 2026

PRELIMINARY PROSPECTUS SUPPLEMENT (To Prospectus dated

Alphabet Inc.

Floating Rate Notes due 20

% Notes due 20 % Notes due 20

% Notes due 20 % Notes due 20

% Notes due 20 % Notes due 20

We are offering aggregate principal amount of our floating rate notes (the “floating rate notes”), aggregate principal amount of our % notes due 20 (the “20 Notes”), aggregate principal amount of our

% notes due 20 (the “20 Notes”), aggregate principal amount of our % notes due 20 (the “20 Notes”), aggregate principal amount of our % notes due 20 (the “20 Notes”), aggregate principal amount of our

% notes due 20 (the “20 Notes”) and aggregate principal amount of our % notes due 20 (the “20 Notes” and, together with the 20 Notes, the 20 Notes, the 20 Notes, the 20 Notes and the 20 Notes, the “fixed rate notes”). The fixed rate notes and the floating rate notes are collectively referred to as the “notes.” The floating rate notes will mature on , 20 , the 20 Notes will mature on , 20 , the 20 Notes will mature on

, 20 , the 20 Notes will mature on , 20 , the 20 Notes will mature on , 20 , the 20 Notes will mature on

, 20 and the 20 Notes will mature on , 20 . Interest on the floating rate notes will accrue from , 2026 and be payable quarterly in arrears on

, , and of each year, beginning on , 2027. The floating rate notes will bear interest at a floating rate equal to the Applicable EURIBOR Rate (as defined in “Description of the Notes—Information about EURIBOR”) based on the three-month EURIBOR, reset quarterly, plus % per annum. Interest on the fixed rate notes will accrue from , 2026 and be payable on of each year, beginning on , 2027. We may redeem any series of the fixed rate notes in whole or in part at any time or from time to time at the redemption prices described under the heading “Description of the Notes—Optional Redemption.” The floating rate notes will not be redeemable prior to maturity, except that we may redeem any series of the notes (including both the fixed rate notes and the floating rate notes) in whole, but not in part, at any time at our option in the event of certain changes in the tax laws of the United States that would require us to pay additional amounts as described under “Description of the Notes—Redemption for Tax Reasons.”

The notes will be our senior unsecured obligations and will rank equally with our other unsecured and unsubordinated indebtedness from time to time outstanding. The notes will be structurally subordinated to all existing and future indebtedness and other obligations of our subsidiaries.

We intend to apply to list each series of the notes on the Nasdaq Bond Exchange (“Nasdaq”). The listing applications will be subject to approval by

Nasdaq. We currently expect trading in each series of the notes on Nasdaq to begin within 30 days after the original issue date. If such a listing is obtained, we have no obligation to maintain such listing and we may delist any series of the notes at any time. Currently, there is no public market for any series of the notes.

See “ Risk Factors ” beginning on page S-7 for a discussion of certain risks that should be considered in connection with an investment in the notes.

The summary below describes the principal terms of the notes. Certain of the terms described below are subject to important limitations and exceptions. The “Description of the Notes” section of this prospectus supplement and the “Description of Debt Securities” section of the accompanying prospectus contain a more detailed description of the terms of the notes. For purposes of this description, references to the “Company,” “we,” “our” and “us” refer only to Alphabet Inc. and not to its subsidiaries.

Issuer Alphabet Inc.

Notes Offered aggregate principal amount of floating rate notes due 20 .

aggregate principal amount of % notes due 20 .

Maturity Dates The floating rate notes will mature on , 20 .

The 20 Notes will mature on

, 20 .

Interest Rates The floating rate notes will bear interest at a floating rate, reset quarterly, on each floating rate interest payment date (as defined in “Description of the Notes—Floating Rate Notes”), equal to the Applicable EURIBOR Rate based on the three-month EURIBOR plus % per annum.

The 20 Notes will bear interest at a rate of % per year.

Interest Payment Dates Interest will be payable quarterly in arrears for the floating rate notes on , , and of each year, beginning on , 2027.

Interest will be payable annually in arrears for the fixed rate notes on of each year, beginning on , 2027.

Currency of Payments Initial holders will be required to pay for the notes in euros, and all payments on the notes will be payable in euros; provided that if on or after the date of this prospectus supplement the euro is unavailable to us due to the imposition of exchange controls or other circumstances beyond our control or if the euro is no longer used by the then Member States of the European Monetary Union that have adopted the euro as their currency or for the settlement of transactions by public institutions of or within the international banking community, then all payments in respect of the notes will be made in U.S. dollars until the euro is again available to us or so used. The amount payable on any date in euros will be converted into U.S. dollars as described under “Description of the Notes—Issuance in Euros; Payment on the Notes.” Any payment in respect of the notes so made in U.S. dollars will not constitute an event of default under the notes or the indenture.

Optional Redemption We may redeem any series of the fixed rate notes in whole or in part at any time or from time to time at the applicable redemption prices.

If we redeem a series of fixed rate notes prior to the applicable Par Call Date (as defined in “Description of the Notes—Optional Redemption”) (or, in the case of the 20 Notes, at any time prior to maturity) for such series, we will pay a redemption price equal to the greater of (i) 100% of the principal amount of the fixed rate notes to be redeemed and (ii) a make-whole premium as provided herein under “Description of the Notes—Optional Redemption.” In the case of any such redemption, we will also pay accrued and unpaid interest, if any, to, but not including, the redemption date.