If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box.  ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.  ☐

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, anon-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,”filer”, “smaller reporting company” and “emerging growth companycompany” in Rule12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

CALCULATION OF REGISTRATION FEE

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until this Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

This registration statement contains two prospectuses:

The base prospectus immediately follows this explanatory note. The specific terms of any securities to be offered pursuant to the base prospectus will be specified in a prospectus supplement to the base prospectus.

The sales agreement prospectus immediately follows the base prospectus. The $50.0 million of common stock that may be offered, issued and sold under the sales agreement prospectus is included in the $150.0 million of securities that may be offered, issued and sold by us under the base prospectus. Upon termination of the Sales Agreements with Cantor Fitzgerald & Co. and B. Riley FBR, Inc., any portion of the $50.0 million included in the sales agreement prospectus that is not sold pursuant to the Sales Agreements will be available for sale in other offerings pursuant to the base prospectus and a corresponding prospectus supplement, and if no shares are sold under the Sales Agreements, the full $150.0 million of securities may be sold in other offerings by us pursuant to the base prospectus and a corresponding prospectus supplement.

discretion to determine the rights, preferences, privileges and restrictions, including voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences, of each series of preferred stock. There are no restrictions presently on the repurchase or redemption of any shares of our preferred stock.

The prospectus supplement for a series of preferred stock will specify:

The issuance of preferred stock will affect, and may adversely affect, the rights of holders of common stock. It is not possible to state the actual effect of the issuance of any shares of preferred stock on the rights of holders

Holders of equity warrants will not be entitled:

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specifyexpressed in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information,Securities Act and paying the required amount to the warrant agent in immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities as all or part of the exercise price for warrants.

Enforceability of Rights by Holders of Warrants

Each warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

DESCRIPTION OF UNITS

We may issue units consisting of any combination of the other types of securities offered under this prospectus in one or more series. We may evidence each series of units by unit certificates that we will issue under a separate agreement. We may enter into unit agreements with a unit agent. Each unit agent will be a bank or trust company that we select. We will indicate the name and address of the unit agent in the applicable prospectus supplement relating to a particular series of units.

The following description, together with the additional information included in any applicable prospectus supplement, summarizes the general features of the units that we may offer under this prospectus. You should read any prospectus supplement and any free writing prospectus that we may authorize to be provided to you related to the series of units being offered, as well as the complete unit agreements that contain the terms of the units. Specific unit agreements will contain additional important terms and provisions and we will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from another report that we file with the SEC, the form of each unit agreement relating to units offered under this prospectus.

If we offer any units, certain terms of that series of units will be described in the applicable prospectus supplement, including, without limitation, the following, as applicable:

Enforceability of Rights by Holders of Units

To the extent applicable, each unit agent will act solely as our agent under the applicable unit agreement and will not assume any obligation or relationship of agency or trust with any holder of any unit. A single bank or trust company may act as unit agent for more than one series of units. A unit agent will have no duty or responsibility in case of any default by us under the applicable unit agreement or unit, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a unit may, without the consent of the related unit agent or the holder of any other unit, enforce by appropriate legal action its rights as holder under any security included in the unit.

We, any unit agents and any of their agents may treat the registered holder of any unit certificate as an absolute owner of the units evidenced by that certificate for any purpose and as the person entitled to exercise the rights attaching to the units so requested, despite any notice to the contrary.therefore unenforceable.

commissions payable to the agent by us. Unless otherwise indicated in the prospectus supplement, any agent will agree to use its reasonable best efforts to solicit purchases for the period of its appointment.

We may sell the securities directly to institutional investors or others who may be deemed to be underwriters“underwriters” within the meaning of the Securities Act, with respect toand any salediscounts, concessions, commissions or fees received by them and any profit on the resale of those securities. The terms of any such sales will be described in the prospectus supplement.

Delayed delivery contracts

If the prospectus supplement indicates, we may authorize agents, underwriters or dealers to solicit offers from certain types of institutions to purchase securities at the public offering price under delayed delivery contracts. These contracts would provide for payment and delivery on a specified date in the future. The contracts would be subject only to those conditions described in the prospectus supplement. The applicable prospectus supplement will describe the commission payable for solicitation of those contracts.

Market making, stabilization and other transactions

Unless the applicable prospectus supplement states otherwise, each series of offered securities will be a new issue and will have no established trading market. We may elect to list any series of offered securities on an exchange. Any underwriters that we use in the sale of offered securities may make a market in such securities, but may discontinue such market making at any time without notice. Therefore, we cannot assure you that the securities will have a liquid trading market.sold by them may be deemed to be underwriting discounts and commissions.

Any underwriterThe Selling Stockholder may alsoenter into hedging transactions with broker-dealers and the broker-dealers may engage in stabilizing transactions, syndicate covering transactions and penalty bids in accordance with Rule 104 under the Securities Exchange Act of 1934, as amended. Stabilizing transactions involve bids to purchase the underlying security in the open market for the purpose of pegging, fixing or maintaining the price of the securities. Syndicate covering transactions involve purchasesshort sales of the securities in the open market aftercourse of hedging the distribution has been completedpositions they assume with that Selling Stockholder, including, without limitation, in order to cover syndicate short positions.

Penalty bids permit the underwriters to reclaim a selling concession from a syndicate member whenconnection with distributions of the securities originallyby those broker-dealers. The Selling Stockholder may enter into options or other transactions with broker-dealers that involve the delivery of the securities offered hereby to the broker-dealers, who may then resell or otherwise transfer those securities. The Selling Stockholder may also loan or pledge the securities offered hereby to a broker-dealer and the broker-dealer may sell the securities offered hereby so loaned or upon a default may sell or otherwise transfer the pledged securities offered hereby.

The Selling Stockholder may also sell the securities in accordance with Rule 144 under the Securities Act, or in accordance with Section 4(a)(1) of the Securities Act, rather than pursuant to this prospectus, regardless of whether the securities are covered by this prospectus.

To comply with the securities laws of some states, if applicable, the securities may be sold in these jurisdictions only through registered or licensed brokers or dealers. In addition, in some states the securities may not be sold unless they have been registered or qualified for sale or an exemption from registration or qualification requirements is available and is complied with.

Such electronic system may allow bidders to directly participate, through electronic access to an auction site, by submitting conditional offers to buy that are subject to acceptance by us, and which may directly affect the price or other terms and conditions at which such securities are sold. These bidding or ordering systems may present to each bidder, on aso-called “real-time” basis, relevant information to assist in making a bid, such as the clearing spread at which the offering would be sold, based on the bids submitted, and whether a bidder’s individual bids would be accepted, prorated or rejected.

Upon completion of such an electronic auction process, securities will be allocated based on prices bid, terms of bid or other factors. The final offering price at which securities would be sold and the allocation of securities among bidders would be based in whole or in part on the results of the Internet or other electronic bidding process or auction.

General information

Agents, underwriters, and dealers may be entitled, under agreements entered into with us, to indemnification by us against certain liabilities,registered hereunder, including liabilities under the Securities Act.

CUSIP NumberAct, and to contribute to payments that the Selling Stockholder may be required to make with respect thereto.

The Committee on Uniform Securities Identification Procedures assigns a unique number, known as a CUSIP number,Selling Stockholder will act independently of us in making decisions with respect to a class or issuethe timing, manner and size of securities in which alleach sale of the securities have similar rights. Certain shares of common stock covered by this prospectus included shares with a CUSIP number based on the shares being issued to an initial purchaser under Rule 144A.

Anyprospectus. We will not receive any proceeds from sales of sharesany securities by the Selling Stockholder. We cannot assure you that the Selling Stockholder will sell all or any portion of our common stockthe securities offered hereby.

To the extent permitted by meansapplicable law, this plan of thisdistribution may be modified in a prospectus must be settled with shares of common stock bearing our general (not necessarily restricted) common stock CUSIP number. The process of obtaining such shares might take a number of business days. SEC rules generally require trades in the secondary market to settle in two business days, unless the parties to any such trade expressly agree otherwise.supplement.

TABLE OF CONTENTS

Prospectus

ABOUT THIS PROSPECTUS

This prospectus relates to the offering of our common stock. Before buying any of the common stock that we are offering, we urge you to carefully read this prospectus, together with the information incorporated by reference as described under the headings “Where You Can Find More Information” and “Incorporation of Certain Information by Reference” in this prospectus. These documents contain important information that you should consider when making your investment decision.

You should rely only on the information contained in, or incorporated by reference into this prospectus and in any free writing prospectus that we may authorize for use in connection with this offering. We have not, and the Agents have not, authorized any other person to provide you with different information. If anyone provides you with additional, different or inconsistent information, you should not rely on it. We are not, and the Agents are not, making an offer to sell or soliciting an offer to buy our common stock in any jurisdiction in which an offer or solicitation is not authorized or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should assume that the information appearing in this prospectus, the documents incorporated by reference into this prospectus, and in any free writing prospectus that we may authorize for use in connection with this offering, is accurate only as of the date of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus the documents incorporated by reference into this prospectus, and any free writing prospectus that we may authorize for use in connection with this offering, in their entirety before making an investment decision.

The distribution of this prospectus and the offering of the common stock in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the common stock and the distribution of this prospectus outside the United States. This prospectus do not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.

We own or have rights to use the trademarks and trade names that we use in conjunction with the operation of our business. Some of the more important trademarks and trade names that we own or have rights to use that appear in this prospectus include: Anterix^™, which may be registered or trademarked in the United States. Each trademark or trade name of any other company appearing in this prospectus is, to our knowledge, owned by such other company. Solely for convenience, our trademarks and trade names referred to in this prospectus may appear without the ^® or^™ symbols, but those references are not intended to indicate, in any way, that we will not assert, to the fullest extent under applicable law, our rights or the right of the applicable licensor to these trademarks and trade names.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains “forward-looking statements” that involve substantial risks and uncertainties. All statements other than statements of historical facts contained in this prospectus, including statements regarding our future results of operations and financial position, strategy and plans, and our expectations for future operations, are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the Securities Act), and Section 21E of the Securities Exchange Act of 1934, as amended (the Exchange Act). Our forward-looking statements are generally, but not always, accompanied by words such as “estimate,” “project,” “predict,” “believe,” “expect,” “anticipate,” “potential,” “should,” “will,” “may,” “plan,” “goal,” “can,” “could,” “continuing,” “ongoing,” “intend” or other words that convey the uncertainty of future events or outcomes. We have based these forward-looking statements on our current expectations and projections, and related assumptions, about future events and financial trends. While our management considers these expectations, projections and assumptions to be reasonable, they are inherently subject to significant business, economic, competitive, regulatory and other risks, contingencies and uncertainties, most of which are difficult to predict and many of which are beyond our control. There can be no assurance that actual developments will be those anticipated by us. Actual results may differ materially from those expressed or implied in these statements as a result of significant risks and uncertainties, including, but not limited to:

All written and verbal 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 section. We caution investors not to rely too heavily on the forward-looking statements we make or that are made on our behalf. We

undertake no obligation, and specifically decline any obligation, to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise.

This prospectus includes statistical and other industry and market data that we obtained from industry publications and research, surveys and studies conducted by third parties. Industry publications and third-party research, surveys and studies generally indicate that their information has been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. While we believe these industry publications and third-party research, surveys and studies are reliable, we have not independently verified such data.

In addition, you should refer to the section of this prospectus entitled “Risk Factors” as well as the documents we have incorporated by reference for a discussion of other important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. As a result of these factors, we cannot assure you that the forward-looking statements in this prospectus will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all.

PROSPECTUS SUMMARY

This summary highlights certain information about us, this offering and selected information contained elsewhere in or incorporated by reference into this prospectus. This summary is not complete and does not contain all of the information that you should consider before deciding whether to invest in our common stock. For a more complete understanding of our company and this offering, we encourage you to read and consider carefully the more detailed information in this prospectus, including the information incorporated by reference into this prospectus and the information included in any free writing prospectus that we have authorized for use in connection with this offering, including the information contained in and incorporated by reference under the heading “Risk Factors” beginning on page 7 of this prospectus, and under similar headings in the other documents that are filed after the date hereof and incorporated by reference into this prospectus.

Overview

We are a wireless communications company focused on empowering the modernization of critical infrastructure and enterprise businesses communications by enabling broadband connectivity. Our foundational spectrum provides the ability to transform our customers operations to meet new business complexities while achieving higher levels of performance and safety. We are the largest holder of licensed spectrum in the 900 MHz band(896-901/935-940 MHz) with nationwide coverage throughout the contiguous United States, Hawaii, Alaska and Puerto Rico. On average, we hold approximately 60% of channels in the 900 MHz band in the top 20 metropolitan market areas in the United States. We are currently pursuing a regulatory proceeding at the Federal Communications Commission (“FCC”) that seeks to modernize and realign the 900 MHz band by allowing it to be utilized for the deployment of broadband networks, technologies and solutions. Our goal is to become the leading provider of broadband spectrum assets to critical infrastructure and enterprise customers. We maintain offices in Woodland Park, New Jersey and McLean, Virginia.

Please see our latest periodic reports filed with the Securities and Exchange Commission regarding our FCC initiatives.

Corporate Information

Our principal executive offices are located at 3 Garret Mountain Plaza, Suite 401, Woodland Park, New Jersey 07424 and 8260 Greensboro Drive, McLean, Virginia. Our main telephone number is(973) 771-0300. We were incorporated in California in 1997, and reincorporated in Delaware in May 2014. In November 2015, we changed our name from Pacific DataVision, Inc. to pdvWireless, Inc. In August 2019 we changed our name from pdvWireless, Inc. to Anterix Inc. Our internet website is currently www.anterix.com. The information on or accessible through our website is not incorporated into this prospectus, and you should not consider any information on, or that can be accessed through, our website a part of this prospectus.

THE OFFERING

The number of shares of common stock that will be outstanding after this offering as shown above is based on 17,146,680 shares of common stock outstanding as of December 31, 2019 and excludes the following, all as of December 31, 2019:

Unless otherwise indicated, all information in this prospectus assumes no exercise of the outstanding options, no vesting or settlement of restricted or performance stock units nor the issuance of awards under the 2014 Stock Plan described above.

RISK FACTORS

An investment in our common stock involves a high degree of risk. You should carefully consider the risks described under “Risk Factors” in our most recent Annual Report on Form10-K and Quarterly Reports on Form10-Q, and all of the other information contained in this prospectus, and incorporated by reference into this prospectus, including our financial statements and related notes, before investing in our common stock.

If any of the possible events described below or in those sections actually occur, our business, business prospects, cash flow, results of operations or financial condition could be harmed, the trading price of our common stock could decline, and you might lose all or part of your investment in our common stock. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our operations and results.

Risks Related to our Business

TheCOVID-19 coronavirus could adversely impact our business, including the timing of our 900 MHz proceeding before the FCC, and financial condition.

On March 12, 2020, the World Health Organization declaredCOVID-19 to be a pandemic. In an effort to contain and mitigate the spread ofCOVID-19, many countries, including the United States, have imposed unprecedented restrictions on travel and business and government operations, and there have been business closures and a substantial reduction in economic activity in countries that have had significant outbreaks ofCOVID-19.

Our plans to commercialize our 900Mhz spectrum assets to support the deployment of broadband networks, technologies and solutions depend on the FCC’s issuance of a favorable Report and Order in the 900 MHz proceeding. Due to reduced governmental operations, the FCC may not issue a Report and Order on a timely basis (or at all), which could significantly delay or increase the costs required to commercialize our spectrum assets compared to the timing and costs we have assumed in our business plan. Even if the referenced FCC initiatives are successful, restrictions on business operations may prevent us from timely and successfully commercializing our spectrum assets to critical infrastructure and enterprise customers.

We may experience further disruptions as a result ofthe COVID-19 pandemic that could severely impact our business, including:

The global outbreak ofthe COVID-19 coronavirus continues to rapidly evolve. The extent to whichthe COVID-19 coronavirus may impact our business will depend on future developments, which are highly uncertain and cannot be predicted with confidence, such as the ultimate geographic spread of the disease, the duration of the outbreak, travel restrictions, required social distancing, and other governmental mandates issued to stop the spread of the disease and its impact in the United States and other countries, business closures or governmental or business

disruptions, and the effectiveness of actions taken in the United States and other countries to contain and treat the virus.

Risks Related to this Offering of our Common Stock

Resales of our common stock in the public market during this offering by our stockholders may cause the market price of our common stock to fall.

We may issue common stock from time to time in connection with this offering. This issuance from time to time of these new shares of our common stock, or our ability to issue these shares of common stock in this offering, could result in resales of our common stock by our current stockholders concerned about the potential dilution of their holdings. In turn, these resales could have the effect of depressing the market price for our common stock.

We have a limited trading history and there is no assurance that a robust market in our common stock will develop or be sustained.

Our common stock began trading on The Nasdaq Capital Market in February 2015. Since our common stock began trading, we have had limited daily trading volume and we cannot assure you that a more active or liquid trading market for our common stock will develop, or will be sustained if it does develop, either of which could materially and adversely affect the market price of our common stock, our ability to raise capital in the future and the ability of stockholders to sell their shares at the volume, prices and times desired.

Our common stock prices may be volatile which could cause the value of our common stock to decline.

Prior to the listing of our shares of common stock on The Nasdaq Capital Market in February 2015, there was no public market for our common stock. The market price of our common stock may be highly volatile and subject to wide fluctuations. Our financial performance, spectrum initiatives, tax laws, interest rates and market conditions in general could have a significant impact on the future market price of our common stock.

Some of the factors that could negatively affect or result in fluctuations in the market price of our common stock include:

You will experience immediate and substantial dilution.

The offering price per share in this offering may exceed the net tangible book value per share of our common stock outstanding prior to this offering. Assuming that an aggregate of $50 million of shares of our common stock are sold at the assumed offering price of $43.06 per share (the last reported sale price of our common stock on The Nasdaq Capital Market on April 1, 2020), and after deducting commissions and estimated aggregate offering expenses payable by us, you will experience immediate dilution of $32.43 per share, representing the difference between our as adjusted net tangible book value per share as of December 31, 2019 after giving effect to this offering and the assumed offering price. In addition, we are not restricted from issuing additional securities in the future, including shares of common stock, securities that are convertible into or exchangeable for, or that represent the right to receive, common stock or substantially similar securities. The issuance of these securities may cause further dilution to our stockholders. The exercise of outstanding stock options and the vesting of outstanding restricted stock units may also result in further dilution of your investment. See the section entitled “Dilution” on page 11 below for a more detailed illustration of the dilution you may incur if you participate in this offering.

You may experience future dilution as a result of future equity offerings.

In order to raise additional capital, we may in the future offer additional shares of our common stock or other securities convertible into or exchangeable for our common stock, including pursuant toour at-the-market sales program, at prices that may not be the same as the price per share in this offering. We cannot assure you that we will be able to sell shares or other securities in any other offering at a price per share that is equal to or greater than the price per share paid by investors in this offering, and investors purchasing shares or other securities in the future could have rights superior to existing stockholders, including investors who purchase shares of common stock in this offering. The price per share at which we sell additional shares of our common stock or securities convertible into our common stock in future transactions may be higher or lower than the price per share in this offering.

Our stockholders may be diluted by the exercise of outstanding options or restricted stock units to purchase common stock.

As of December 31, 2019, we had (i) outstanding stock options to purchase 1,815,436 shares of our common stock, issuable at a weighted average exercise price of $23.54 per share, (ii) outstanding performance stock options to purchase 179,945 shares of our common stock, issuable at a weighted average exercise price of $25.83 per share, (iii) 352,584 shares of our common stock issuable upon the vesting and settlement of outstanding restricted stock units, (iv) 120,445 shares of our common stock issuable upon the vesting and settlement of outstanding performance stock units, (v) 801,273 shares of common stock reserved for future grants under our 2014 Stock Plan and the annual increases in the number of shares authorized under our 2014 Stock Plan with the next occurring on January 1, 2021 and (vi) 500,000 shares of common stock issuable to Motorola Solution, Inc. upon conversion of the Class B Units of our subsidiary, PDV Spectrum Holding Company, LLC, issued to Motorola. You may incur dilution upon the issuance of such shares, or shares upon exercise or settlement of such outstanding options or restricted stock units, as applicable.

Our management will have broad discretion over the actual amounts and timing of the expenditures of the proceeds we receive in this offering and might not apply the proceeds in ways that enhance our operating results or increase the value of your investment.

We expect to use the net proceeds from this offering primarily for working capital, pursuing our regulatory initiatives at the FCC, other corporate expenses, and acquisitions of assets, licenses, products, technologies or businesses, although we have no current commitments or agreements with respect to any such acquisitions as of the date of this prospectus. Our management will have broad discretion as to the actual amounts and timing of the expenditures of the net proceeds from this offering, and you will be relying on the judgment of our management

regarding the application of these proceeds. Our management might not apply the net proceeds of this offering in ways that enhance our operating results or increase the value of your investment. Additionally, until the net proceeds we receive are used, they may be placed in investments that do not produce income or that lose value.

USE OF PROCEEDS

We will retain broad discretion over the use of the net proceeds from the sale of our securities offered hereby. Except as described in any free writing prospectus that we may authorize to be provided to you, we currently anticipate using the net proceeds from the sale of the shares offered hereby for general corporate purposes, which may include, among other purposes, working capital, pursuing our regulatory initiatives at the FCC, capital expenditures, other corporate expenses, and acquisitions of assets, licenses, spectrum, products, technologies or businesses, although we have no current commitments or agreements with respect to any such acquisitions as of the date of this prospectus.

The timing and amount of our actual expenditures will be based on many factors, including cash flows from operations and the anticipated growth of our business. As a result, our management will have broad discretion to allocate the net proceeds of the offerings. Pending their ultimate use, we intend to invest the net proceeds in short-term, investment-grade, interest-bearing instruments.

DIVIDEND POLICY

We have never declared or paid any dividends on our common stock and do not anticipate paying any in the foreseeable future. We currently intend to retain all of our future earnings, if any, to finance our business strategy. Any future determination relating to our dividend policy will be made at the discretion of our Board of Directors and will depend on a number of factors, including future earnings, capital requirements, financial conditions, future prospects, contractual restrictions and covenants and other factors that our Board of Directors may deem relevant.

DILUTION

If you invest in this offering, your ownership interest will be diluted to the extent of the difference between the public offering price per share and the as adjusted net tangible book value per share after giving effect to this offering. We calculate net tangible book value per share by dividing the net tangible book value, which is tangible assets less total liabilities, by the number of outstanding shares of our common stock. Dilution represents the difference between the portion of the amount per share paid by purchasers of shares in this offering and the as adjusted net tangible book value per share of our common stock immediately after giving effect to this offering. Our net tangible book value as of December 31, 2019 was approximately $145.7 million, or $8.50 per share.

After giving effect to the sale of our common stock during the term of the Sales Agreements with the Agents in the aggregate amount of $50 million at an assumed offering price of $43.06 per share, the last reported sale price of our common stock on The Nasdaq Capital Market on April 1, 2020, and after deducting commissions and estimated aggregate offering expenses payable by us, our net tangible book value as of December 31, 2019 would have been approximately $194.6 million, or approximately $10.63 per share of common stock. This represents an immediate increase in the net tangible book value of approximately $2.13 per share to our existing stockholders and an immediate dilution in net tangible book value of approximately $32.43 per share to new investors.

The table above assumes for illustrative purposes that an aggregate of 1,161,170 shares of our common stock are sold pursuant to the terms of the Sales Agreements with the Agents at a price of $43.06 per share, the last reported sale price of our common stock on The Nasdaq Capital Market on April 1, 2020, for aggregate gross proceeds of $50 million. The shares sold in this offering, if any, will be sold from time to time at various prices. An increase of $4.00 per share in the price at which the shares are sold from the assumed offering price of $43.06 per share shown in the table above, assuming all of our common stock in the aggregate amount of $50 million is sold at that price, would increase our adjusted net tangible book value per share after the offering from $10.63 per share to $10.69 per share and would increase the dilution in net tangible book value per share to new investors in this offering to $36.37 per share, after deducting commissions and estimated offering expenses payable by us. A decrease of $4.00 per share in the price at which the shares are sold from the assumed offering price of $43.06 per share shown in the table above, assuming all of our common stock in the gross aggregate amount of $50 million is sold at that price, would decrease our adjusted net tangible book value per share after the offering from $10.63 per share to $10.56 per share and would decrease the dilution in net tangible book value per share to new investors in this offering to $28.50 per share, after deducting commissions and estimated offering expenses payable by us. This information is supplied for illustrative purposes only.

The information and table above are based on 17,146,680 shares of common stock outstanding as of December 31, 2019 and excludes the following, all as of December 31, 2019:

To the extent options or restricted stock units outstanding as of December 31, 2019 have been or may be exercised or settled or other shares have been issued, there may be further dilution to investors. In addition, we may choose to raise additional capital due to market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our stockholders.

PLAN OF DISTRIBUTION

We have previously entered into a Controlled Equity Offering^SM Sales Agreement and a Sales Agreement with Cantor Fitzgerald & Co. and B. Riley FBR, Inc., respectively (each an “Agent” and together, the “Agents”), which we have amended and restated (as amended and restated, collectively, the “Sales Agreements”)) under which we may offer and sell shares of our common stock having an aggregate gross sales price of up to $50 million from time to time through the Agents. The Sales Agreements have been filed as exhibits to the FormS-3 of which this prospectus forms a part.

Upon delivery of a placement notice and subject to the terms and conditions of the Sales Agreements, the Agents may sell shares of our common stock, if any, under this prospectus, may be made in sales deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act, including sales made directly on or through The Nasdaq Capital Market or any other existing trading market for our common stock. We or the Agents may suspend the offering of our common stock upon notice and subject to other conditions.

We will pay the Agents commissions, in cash, for their services in acting as agents in the sale of our common stock. The Agents will be entitled to compensation under the terms of the Sales Agreements at a commission rate of up to 2.0% of the gross sales price per share sold. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. We have also agreed to reimburse each of the Agents for certain specified expenses, including the fees and disbursements of their legal counsel in an amount not to exceed $50,000 to each Agent. We estimate that the total expenses for the offering, excluding compensation and reimbursements payable to the Agents under the terms of the Sales Agreement, will be approximately $150,000.

Settlement for sales of common stock will occur on the second business day following the date on which any sales are made, or on some other date that is agreed upon by us and the applicable Agent in connection with a particular transaction or as otherwise required by law, in return for payment of the net proceeds to us. Sales of our common stock as contemplated in this prospectus will be settled through the facilities of The Depository Trust Company or by such other means as we and the Agents may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

The Agents will use their respective commercially reasonable efforts, consistent with their respective sales and trading practices, to solicit offers to purchase the common stock shares under the terms and subject to the conditions set forth in the Sales Agreements. In connection with the sale of the common stock on our behalf, each Agent will be deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of the Agents will be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to the Agents against certain civil liabilities, including liabilities under the Securities Act.

The offering of our common stock pursuant to the Sales Agreements will terminate upon the termination of the Sales Agreements as permitted therein. We and the Agents may each terminate the respective Sales Agreements at any time upon ten days’ prior notice.

The Agents and their respective affiliates may in the future provide various investment banking, commercial banking and other financial services for us and our affiliates, for which services they may in the future receive customary fees. To the extent required by Regulation M, the Agents will not engage in any market making activities involving our common stock while the offering is ongoing under this prospectus.

This prospectus in electronic format may be made available on websites maintained by the respective Agents, and the Agents may distribute this prospectus electronically.

LEGAL MATTERS

The validity of the shares of common stock being offered by this prospectus will be passed upon for us by Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP, San Diego, California. Certain attorneys affiliated with Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP collectively own an aggregate of 6,952 shares of our common stock. Cantor Fitzgerald & Co. and B. Riley FBR, Inc. are being represented in connection with this offering by Cooley LLP, New York, New York.

EXPERTS

The audited consolidated financial statements of Anterix Inc. and subsidiaries as of March 31, 2019 and for the year then ended incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the report of Grant Thornton LLP, independent registered public accountants, upon the authority of said firm as experts in accounting and auditing.

The consolidated financial statements of Anterix Inc. and subsidiary as of March 31, 2018 and for each of the two years ended March 31, 2018, have been incorporated herein by reference in reliance upon the report of PKF O’Connor Davies, LLP, an independent registered public accounting firm, given upon the authority of said firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We have filed a registration statement onForm S-3, including exhibits, under the Securities Act with respect to the securities offered by this prospectus. This prospectus is part of that registration statement, but does not contain all of the information included in the registration statement or the exhibits.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC’s website at www.sec.gov.

Our common stock is listed on The Nasdaq Capital Market under the symbol “ATEX.” General information about our company, including our Annual Report on Form10-K, Quarterly Reports on Form10-Q and Current Reports on Form8-K, as well as any amendments and exhibits to those reports, are available free of charge through our website at www.anterix.com as soon as reasonably practicable after we file them with, or furnish them to, the SEC. Information on, or than can be accessed through, our website is not incorporated into this prospectus or other securities filings and is not a part of these filings.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” into this prospectus the information we file with it, which means that we can disclose important information to you by referring you to those documents. The information we incorporate by reference is an important part of this prospectus, and later information that we file with the SEC will automatically update and supersede some of this information. We incorporate by reference the documents listed below and any future filings we make with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the Exchange Act), including filings made after the date of the initial registration statement, until we sell all of the shares covered by this prospectus or the sale of shares by us pursuant to this prospectus is terminated. In no event, however, will any of the information that we furnish to, pursuant to Item 2.02 or Item 7.01 of any Current Report on Form8-K (including exhibits related thereto) or other applicable SEC rules, rather than file with, the SEC be incorporated by reference or otherwise be included herein, unless such information is expressly incorporated herein by a reference in such furnished Current Report on Form8-K or other furnished document. The documents we incorporate by reference are:

Any statement contained in a document incorporated or deemed to be incorporated by reference into this prospectus will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or any other subsequently filed document that is deemed to be incorporated by reference into this prospectus modifies or supersedes the statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

We will provide each person to whom a prospectus is delivered a copy of all of the information that has been incorporated by reference in this prospectus but not delivered with the prospectus. You may obtain copies of these filings, at no cost, through the “Investor Relations” section of our website (www.anterix.com) and you may request a copy of these filings (other than an exhibit to any filing unless we have specifically incorporated that exhibit by reference into the filing), at no cost, by writing or telephoning us at the following address:

Anterix Inc.

Attn: Investor Relations

3 Garret Mountain Plaza, Suite 401

Woodland Park, New Jersey

(973)771-0300

Information on, or that can be accessed through, our website is not incorporated into this prospectus or other securities filings and is not a part of these filings.

Up to $50,000,000

Common Stock

PROSPECTUS

            , 2020

Part II

Information Not Required in the Prospectus

The following table sets forth the estimated costs and expenses (other than the actual registration fee and FINRA filing fee), other than underwriting discounts and commissions, payable by the registrant in connection with the sale of the securities being registered.

Section 102(b)(7) of the Delaware General Corporation Law allows a corporation to provide in its certificate of incorporation that a director of the corporation will not be personally liable to the corporation or its stockholders for monetary damages for breach of fiduciary duty as a director, except where the director breached the duty of loyalty, failed to act in good faith, engaged in intentional misconduct or knowingly violated a law, authorized the payment of a dividend or approved a stock repurchase in violation of Delaware corporate law or obtained an improper personal benefit.

Section 145(a) of the Delaware General Corporation Law provides that a Delaware corporation may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that such person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation or enterprise, against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with such action, suit or proceeding if he or she acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, had no cause to believe his or her conduct was unlawful.

Section 145(b) of the Delaware General Corporation Law provides that a Delaware corporation may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by or in the right of the corporation to procure a judgment in its favor by reason of the fact that such person acted in any of the capacities set forth above, against expenses (including attorneys’ fees) actually and reasonably incurred by such person in connection with the defense or settlement of such action or suit if he or she acted under similar standards, except that no indemnification may be made in respect of any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the court in which such action or suit was brought shall determine that, despite the adjudication of liability but in view of all the circumstances of the case, such person is fairly and reasonably entitled to be indemnified for such expenses which the court shall deem proper.

Section 145 of the Delaware General Corporation Law further provides that: (i) to the extent that a former or present director or officer of a corporation has been successful in the defense of any action, suit or proceeding referred to in subsections (a) and (b) or in the defense of any claim, issue or matter therein, such person shall be

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indemnified against expenses (including attorneys’ fees) actually and reasonably incurred by him or her in

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(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the SEC pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20 percent change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the SEC by the registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

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SignaturesSIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on FormS-3 and has duly caused this registration statement on FormS-3 to be signed on its behalf by the undersigned, thereunto duly authorized, in Woodland Park, State of New Jersey, on April 3, 2020.June 30, 2022.

Power of Attorney

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Robert H. Schwartz and Timothy A. Gray, and Gena Ashe, and each of them acting individually, as his or her true and lawfulattorneys-in-fact and agents, with full power of each to act alone, with full powers of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments to this registration statement onForm S-3 (including post-effective amendments and any related registration statements filed pursuant to Rule 462 and otherwise) with all exhibits thereto and all documents in connection therewith, with the Securities and Exchange Commission, granting unto saidattorneys-in-fact and agents, with full power of each to act alone, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully for all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that saidattorneys-in-fact and agents, or his or her or their substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

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