Micron Technology : 424B2

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Filed pursuant to Rule 424(b)(2)

Registration No. 333-220882

This preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these notes has been filed with the U.S. Securities and Exchange Commission and is effective. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these notes and they are not soliciting an offer to buy these notes in any jurisdiction where the offer or sale is not permitted.

Subject to Completion, dated February 4, 2019

Preliminary Prospectus Supplement

(To Prospectus dated October 10, 2017)

$

Micron Technology, Inc.

• $ % Senior Notes due 20

• $ % Senior Notes due 20

• $ % Senior Notes due 20

Micron Technology, Inc. is offering $ aggregate principal amount of

% senior notes due 20 (the "20

principal amount of % senior notes due 20 (the "20 " notes) and $ aggregate principal amount ofnotes"), $ aggregate % senior notes due 20 (the

"20 notes" and, together with the 20 notes and the 20 notes, the "notes"). The 20 notes, the 20 notes and the 20 herein as a series of notes.

notes are each referred toThe 20

notes will bear interest at the rate of % per year, the 20 notes will bear interest at the rate ofinterest at the rate of 2019.

% per year. Interest will be payable semi-annually in arrears on and

% per year and the 20 of each year, beginning

notes will bear ,

The 20 20 .

notes will mature on

, 20

the 20

notes will mature on

, 20

and the 20

notes will mature on

,We may redeem some or all of the notes, at any time or from time to time, at a redemption price equal to the greater of (i) 100% of the principal amount of the notes to be redeemed and (ii) a make-whole amount (as described in the section entitled "Description of the Notes-Optional Redemption"), plus accrued and unpaid interest thereon to, but excluding, the redemption date. In addition, we may redeem the 20 notes in whole or in part, at any time from or after , 20 , the 20 notes in whole or in part, at any time from or after , 20 , and the 20 notes in whole or in part, at any time from or after , 20 , at a redemption price equal to 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest thereon to, but excluding, the redemption date. See "Description of the Notes-Optional Redemption" in this prospectus supplement for more information. We will be required to make an offer to purchase each series of the notes, at a price equal to 101% of their principal amount, plus accrued and unpaid interest to, but excluding, the date of purchase, upon the occurrence of a Change of Control Triggering Event (as defined herein). See the section entitled "Description of the Notes-Repurchase of Notes Upon a Change of Control Triggering Event" for more information.

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

Investing in the notes involves risks. 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.

Neither the U.S. Securities and Exchange Commission nor any state securities commission has approved or disapproved of the notes or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Per 20 Note 20 Notes Total Per 20 Note 20 Notes Total Per 20 Note

• 20 Notes Total

  Proceeds
  Public offering	Underwriting	to us, before
  price(1)	discounts(2)	expenses(1)
  %	%

  % % %

  Total

  $ $ $ $

  $ $ $ $

  % %

  $ $ $ $

  % %

• (1) Plus accrued interest, if any, from

  , 2019.

• (2) The underwriters have agreed to reimburse us for certain expenses in connection with the offering. See "Underwriting."Interest on the notes will accrue from

, 2019. The notes will be issued in registered, book-entry form only without interest coupons, inminimum denominations of $2,000 and integral multiples of $1,000 in excess thereof. The notes will not be listed on any securities exchange. Currently there is no public market for the notes.

The underwriters expect to deliver the notes to purchasers through the book-entry delivery system of The Depository Trust Company and its participants, including Euroclear Bank S.A./N.V. and Clearstream Banking, S.A. on or about , 2019.

Joint Book-Running Managers

Morgan Stanley

BNP PARIBAS

Credit Suisse

, 2019

Table of Contents
Page
Cautionary Note on Forward-Looking Statements	S-ii
About This Prospectus Supplement	S-ii
Summary	S-1
Risk Factors	S-7
Use of Proceeds	S-11
Cash and Capitalization	S-12
Description of the Notes	S-13
Material U.S. Federal Income Tax Consequences	S-37
Underwriting	S-42
Validity of Securities	S-47
Experts	S-47
Where You Can Find More Information	S-47
Page
About This Prospectus	1
Where You Can Find More Information; Incorporation by Reference	2
The Company	4
Risk Factors	5
Use of Proceeds	6
Ratio of Earnings to Fixed Charges	7
Description of Securities	8
Plan of Distribution	9
Legal Matters	10
Experts	10

TABLE OF CONTENTS

Prospectus SupplementProspectus

S-i

CAUTIONARY NOTE ON FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the information incorporated herein and therein by reference include statements that are, or may be deemed, "forward-looking statements." You can identify forward-looking statements by the use of forward-looking terminology including "anticipates," "believes," "estimates," "expects," "future," "intends," "may," "plans," "potential," "predicts," "projects," "should," "will," "would" and similar expressions or the negative of these words and phrases, other variations of these words and phrases or comparable terminology.

The forward-looking statements relate to, among other things:

•

statements such as those made regarding our expected NAND and 3D XPointTM development activities with Intel Corporation ("Intel");

•

the exercise of our call option to purchase Intel's interest in IM Flash Technologies, LLC ("IM Flash") and the amount we expect to pay for the transaction;

•

our expectation, from time to time, to engage in additional financing transactions;

•

the sufficiency of our cash and investments, cash flows from operations, and available financing to meet our requirements at least through the next 12 months; and

•

capital spending in 2019.

Our actual results could differ materially from our historical results and those discussed in the forward-looking statements. Factors that could cause actual results to differ materially include, but are not limited to those identified in the section titled "Risk Factors" of this prospectus supplement and in our Annual Report on Form 10-K and our Quarterly Report on Form 10-Q incorporated by reference herein and as may be updated in filings we make with the U.S. Securities and Exchange Commission (the "SEC"). The forward-looking statements contained herein are based on information available to us as of the date of this prospectus supplement and are based on management's current views and assumptions and should not be relied upon as representing our views as of any subsequent date.

All subsequent written and oral forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this prospectus supplement and any other cautionary statements that may accompany such forward-looking statements. We do not undertake any obligation to release publicly any revisions to these forward-looking statements to reflect events or circumstances after the date of this document or to reflect the occurrence of unanticipated events, unless the securities laws require us to do so.

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus dated October 10, 2017 are part of a registration statement that we filed with the SEC, using a "shelf" registration process. Under this shelf registration process, we may from time to time offer to sell securities, in one or more offerings. We provide information to you about this offering of the notes in two separate documents that are bound together: (1) this prospectus supplement, which describes the specific details regarding this offering; and (2) the accompanying prospectus, which provides general information, some of which may not apply to this offering. Generally, when we refer to this "prospectus," we are referring to both documents combined. If information in this prospectus supplement is inconsistent with the accompanying prospectus, you should rely on this prospectus supplement. However, if any statement in one of these documents is inconsistent with a statement in another document having a later date-for example, a document incorporated by reference in the accompanying prospectus -the statement in the document having the later date modifies or supersedes the earlier statement as our business, financial condition, results of operations and prospects may have changed since the earlier dates. You should read this prospectus supplement, the accompanying prospectus, the documents and information incorporated by reference in this prospectus supplement and

S-ii

the accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering when making your investment decision. You should also read and consider the information in the documents we have referred you to under the heading "Where You Can Find More Information."

You should rely only on the information contained in or incorporated by reference in this prospectus supplement, the accompanying prospectus or in any related free writing prospectus filed by us with the SEC. Neither we nor the underwriters have authorized anyone to provide you with different information. This prospectus supplement and the accompanying prospectus do not constitute an offer to sell or the solicitation of an offer to buy our securities other than the notes described in this prospectus supplement or an offer to sell or the solicitation of an offer to buy the notes in any circumstances in which such offer or solicitation is unlawful. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference and any related free writing prospectus is accurate only as of their respective dates or as otherwise specified therein. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

You should not consider any information in this prospectus supplement or the accompanying prospectus to be investment, legal or tax advice. You should consult your own counsel, accountants and other advisers for legal, tax, business, financial and related advice regarding the purchase of the notes offered by this prospectus supplement.

Unless the context requires otherwise or unless otherwise specified, references in this prospectus supplement to "Micron," "we," "our," "us" and the "Company" refer to Micron Technology, Inc. and our consolidated subsidiaries.

S-iii