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As filed with the Securities and Exchange Commission on November 3, 2016July 16, 2021

Registration No. 333-                

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION
WASHINGTON,

Washington, D.C. 20549

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.  o☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, or an emerging growth company. See the definitions of "large“large accelerated filer," "accelerated filer"” “accelerated filer,” “smaller reporting company,” and "smaller reporting company"“emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one).

The information in this prospectus is not complete and may be changed. We may not sell these securities such indeterminate number of warrants, rightsor accept an offer to buy these securities until the registration statement filed with the Securities and purchase contractsExchange Commission is effective. This prospectus is not an offer to purchase common stock, preferred stock or debtsell these securities, and such indeterminate number of units, as shall have an aggregate initial offering price not to exceed $175,000,000. If any debt securities are issued at an original issue discount, then the offering price of such debt securities shall be in such greater principal amount as shall result in an aggregate initial offering price not to exceed $175,000,000, less the aggregate dollar amount of all securities previously issued hereunder. Any securities registered hereunder may be sold separately or as units with other securities registered hereunder. The proposed maximum initial offering price per unit will be determined, from time to time, by the registrant in connection with the issuance by the registrant of the securities registered hereunder. The securities registered also include such indeterminate number of shares of common stock and preferred stock and amount of debt securities as may be issued upon conversion of or exchange for preferred stock or debt securities that provide for conversion or exchange, upon exercise of warrants or rights or performance of purchase contracts or pursuant to the anti-dilution provisions of any such securities. In addition, pursuant to Rule 416 under the Securities Act of 1933, as amended, the shares being registered hereunder include such indeterminate number of shares of common stock and preferred stock as may be issuable with respect to the shares being registered hereunder as a result of stock splits, stock dividends or similar transactions.

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, AS AMENDED, OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(a), MAY DETERMINE.offer or sale is not permitted.

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EXPLANATORY NOTE

        This registration statement contains:

•

a base prospectus which covers the offering, issuance and sale by us of up to $175,000,000 in the aggregate of the securities identified above from time to time in one or more offerings; and



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a sales agreement prospectus covering the offering, issuance and sale by us of up to a maximum aggregate offering price of $50,000,000 of our common stock that may be issued and sold from time to time under a sales agreement with Cowen and Company, LLC.

        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 $50,000,000 of common stock that may be offered, issued and sold under the sales agreement prospectus is included in the $175,000,000 of securities that may be offered, issued and sold by us under the base prospectus.

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THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER TO SELL THESE SECURITIES AND IS NOT SOLICITING AN OFFER TO BUY THESE SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

SUBJECT TO COMPLETION, DATED NOVEMBER 3, 2016JULY 16, 2021

PROSPECTUS

OvaScience, Inc.

$175,000,000

COMMON STOCK
PREFERRED STOCK
DEBT SECURITIES
WARRANTS
RIGHTS
PURCHASE CONTRACTS
UNITS

 This prospectus will allow us

$250,000,000

Common Stock

Preferred Stock

Debt Securities

Warrants

Units

Rights to issue, fromPurchase Common Stock, Preferred Stock,

Debt Securities or Units

From time to time, at prices and on terms to be determined at or prior to the time of the offering,we may offer up to $175,000,000$250,000,000 of any combination of the securities described in this prospectus either individuallyin one or in units.more offerings. We may also offer common stock or preferred stocksecurities as may be issuable upon conversion, ofredemption, repurchase, exchange or exchange for the debt securities; common stock upon conversion of or exchange for the preferred stock; common stock, preferred stock or debt securities upon the exercise of warrants, rights or performance of purchase contracts; or any combination of these securities upon the performance of purchase contracts.registered hereunder, including any applicable anti-dilution provisions.

This prospectus describesprovides a general description of the general terms of these securities and the general manner in which thesewe may offer. Each time we offer securities, will be offered. Wewe will provide you with the specific terms of any offeringthe securities offered in a supplement to this prospectus. We may also authorize one or more supplementsfree writing prospectuses to this prospectus.be provided to you in connection with these offerings. The prospectus supplements will also describe the specific manner in which these securities will be offeredsupplement and any related free writing prospectus may also supplement,add, update or amendchange information contained in this document.prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, supplement, as well as any documents incorporated by reference, into this prospectus or any prospectus supplement, carefully before you invest.invest in any of the securities being offered.

        OurWe will sell these securities may be sold directly by us to you,investors, through agents designated from time to time or to or through underwriters or dealers.dealers, on a continuous or delayed basis. For additional information on the methods of sale, you should refer to the section entitled "Plan“Plan of Distribution"Distribution” in this prospectus and in the applicable prospectus supplement.prospectus. If any underwritersagents or agentsunderwriters are involved in the sale of ourany securities with respect to which this prospectus is being delivered, the names of such underwritersagents or agentsunderwriters and any applicable fees, commissions, discounts or discounts and over- allotmentover-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds that we expect to receive from such sale will also be set forth in a prospectus supplement.

This prospectus may not be used to consummate a sale of any securities unless accompanied by a prospectus supplement.

Our common stock is listedtraded on The NASDAQ Globalthe Nasdaq Capital Market under the symbol "OVAS."“TPST.” On November 2, 2016,July 15, 2021, the last reported sale price of our common stock was $5.00$19.43 per share. The applicable

We are a “smaller reporting company” under federal securities laws and as such, have elected to comply with reduced public company reporting requirements for this prospectus supplement will contain information, where applicable, asand the documents incorporated by reference herein and may elect to any other listing, if any, on The NASDAQ Global Market or any securities market or other securities exchangecomply with reduced public company reporting requirements in future filings. See “Summary—Implications of the securities covered by the prospectus supplement. Prospective purchasers of our securities are urged to obtain current information as to the market prices of our securities, where applicable.Being a Smaller Reporting Company.”

Investing in our securities involves a high degree of risk. Before deciding whether to invest in our securities, youYou should considerreview carefully the risks and uncertainties described under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that we haveare incorporated by reference into this prospectus as described on page  43 of this prospectus under the caption "Risk Factors." We may include specific risk factors in supplements to this prospectus under the caption "Risk Factors." This prospectus may not be used to sell our securities unless accompanied by a prospectus supplement.

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

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

The date of this prospectus is                 , 2016.2021.

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ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or SEC, utilizing a "shelf"“shelf” registration process. Under this shelf registration process, we may offer sharessell any combination of our common stock and preferred stock, various series of debtthe securities and/or warrants, rights or purchase contracts to purchase any of such securities, either individually ordescribed in units,this prospectus in one or more offerings withup to a total valueaggregate offering price of up to $175,000,000.$250,000,000. This prospectus provides you with a general description of the securities we may offer.

Each time we offer a type or series ofsell securities under this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of that offering.

        This prospectus does not We may also authorize one or more free writing prospectuses to be provided to you that may contain all of thematerial information included in the registration statement. For a more complete understanding of the offering of the securities, you should referrelating to the registration statement, including its exhibits.these offerings. The prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change information contained or incorporated by reference in this prospectus. However, no prospectus supplement will offer a security that is not registered and described in this prospectus at the time of its effectiveness. This prospectus, together with the applicable prospectus supplements and theor in any documents that we have incorporated by reference into this prospectus, includes all material information relating to the offering of securities under this prospectus. You should carefully read this prospectus, theany applicable prospectus supplement and any related free writing prospectus, together with the information and documents incorporated herein by reference and the additional informationas described under the heading "Where You Can Find More Information"“Incorporation of Certain Information by Reference,” before making an investment decision.investing in any of the securities offered.

        You should rely only on theTHIS PROSPECTUS MAY NOT BE USED TO CONSUMMATE A SALE OF SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

Neither we, nor any agent, underwriter or dealer has authorized any person to give any information we have providedor to make any representation other than those contained or incorporated by reference in this prospectus, any applicable prospectus supplement or any related free writing prospectus supplement. We have not authorized anyone to provide you with information different from that containedprepared by or incorporated by reference in this prospectus. No dealer, salesperson or other person is authorized to give any informationon behalf of us or to represent anything not contained or incorporated by reference in this prospectus. You must not rely on any unauthorized information or representation.which we have referred you. This prospectus, isany applicable supplement to this prospectus or any related free writing prospectus do not constitute an offer to sell onlyor the solicitation of an offer to buy any securities offered hereby, but only under circumstances andother than the registered

i

securities to which they relate, nor do this prospectus, any applicable supplement to this prospectus or any related free writing prospectus constitute an offer to sell or the solicitation of an offer to buy securities in jurisdictions whereany jurisdiction to any person to whom it is lawfulunlawful to do so. make such offer or solicitation in such jurisdiction.

You should not assume that the information contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus supplement is accurate only as ofon any date subsequent to the date set forth on the front of the document andor that any information we have incorporated herein by reference is accurate only as ofcorrect on any date subsequent to the date of the document incorporated by reference, regardlesseven though this prospectus, any applicable prospectus supplement or any related free writing prospectus is delivered, or securities are sold, on a later date.

This prospectus and the information incorporated herein by reference contain summaries of certain provisions contained in some of the timedocuments described herein, but reference is made to the actual documents for complete information. All of deliverythe summaries are qualified in their entirety by the actual documents. Copies of this prospectussome of the documents referred to herein have been filed, will be filed or any sale of a security.

        We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that iswill be incorporated by reference inas exhibits to the accompanyingregistration statement of which this prospectus were made solely foris a part, and you may obtain copies of those documents as described below under the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.heading “Where You Can Find More Information.”

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RISK FACTORS

Investing in our securities involves risks. Therefore,a high degree of risk. You should carefully considerreview the risk factors set forthrisks and uncertainties described under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, supplements and under similar headings in our most recent annualAnnual Report on Form 10-K, as updated by any subsequently filed periodic reports and quarterly filings with the SEC, as well as other information in this prospectus and any prospectus supplements and the documents that are incorporated by reference herein or therein,into this prospectus, including the Current Report on Form 8-K filed on July 16, 2021, before purchasing our securities.deciding whether to purchase any of the securities being registered pursuant to the registration statement of which this prospectus is a part. Each of the risk factors described in the documents referenced above could adversely affect our business, operating results and financial condition, as well as adversely affect the value of an investment in our securities.

About OvaScience, Inc.

        OvaScience is a global fertility company focused onsecurities, and the discovery, development, and commercialization of new fertility treatment options for women. The current standard of treatment for infertility is in vitro fertilization, or IVF. IVF, however, fails approximately 70% of the time. The discovery of egg precursor, or EggPC^SM, cells countered a long-held medical belief that women are born with a set number of eggs, and this discovery enabled our new fertility treatment options. Our patented technology is based on these EggPC cells, which are immature egg cells found in the protective outer lining of a woman's ovaries. We believe that these immature egg cells have the ability to grow into young, fertilizable eggs.

        Our portfolio of fertility treatment options uses our patented technology including proprietary methods to identify and isolate EggPC cells from a patient's own ovarian tissue. By applying our EggPC technology platform in unique ways, we have commercialized one fertility treatment and are developing new fertility treatment options that are designed to improve egg health and revolutionize IVF.

Additional Information

        For additional information related to our business and operations, please refer to the reports incorporated herein by reference, including our Annual Report on Form 10-K for the year ended December 31, 2015, as described under the caption "Incorporation of Documents by Reference" on page 24 of this prospectus.

Our Corporate Information

        We were originally incorporated in the State of Delaware in April 2011 under the name "Ovastem, Inc." As used herein, the words "OvaScience," "OVAS," the "Company," "we," "us," and "our" refer to OvaScience, Inc. and our subsidiaries.

        Our corporate headquarters are located at 9 Fourth Avenue, Waltham, Massachusetts 02451 and our telephone number is (617) 500-2802. We maintain a website atwww.ovascience.com, to which we regularly post copies of our press releases as well as additional information about us. The information contained on, or that can be accessed through, our website is not a part of this prospectus. We have included our website address in this prospectus solely as an inactive textual reference.

        All brand names or trademarks appearing in this prospectus are the property of their respective holders. Use or display by us of other parties' trademarks, trade dress, or products in this prospectus is not intended to, and does not, imply a relationship with, or endorsements or sponsorship of, us by the trademark or trade dress owners.

USE OF PROCEEDS

We will retain broad discretion over the use of the net proceeds from the sale of the securities offered hereby. Except as described in any applicable prospectus supplement or in any free writing prospectuses that we may authorize to be provided to you in connection with a specific offering, we currently intend to use the "Risk Factors" section,net proceeds from the sale of the securities offered hereby for working capital, capital expenditures and general corporate purposes. We may also use a portion of the net proceeds to invest in or acquire businesses or technologies that we believe could cause actual resultsare complementary to our own, although we have no current plans, commitments or eventsagreements with respect to differ materially from the forward-looking statements that we make. For a summary of such factors, please refer to the section entitled "Risk Factors" in this prospectus, as updated and supplemented by the discussion of risks and uncertainties under "Risk Factors" contained in any supplements to this prospectus and in our most recent annual report on Form 10-K, as revised or supplemented by our subsequent quarterly reports on Form 10-Q or our current reports on Form 8-K, as well as any amendments thereto, as filed with the SEC and which

DESCRIPTION OF CAPITAL STOCK

The following description is a general summary of short-term indebtedness.

PLAN OF DISTRIBUTION

        We may offer securities under this prospectus from time to time pursuant to underwritten public offerings, negotiated transactions, block trades or a combination of these methods. We may sell the securities (1) through underwriters or dealers, (2) through agents or (3) directly to one or more purchasers, or through a combination of such methods. We may distribute the securities from time to time in one or more transactions at:

•

a fixed price or prices, which may be changed from time to time;



•

market prices prevailing at the time of sale;



•

prices related to the prevailing market prices; or



•

negotiated prices.

        We may directly solicit offers to purchase the securities being offered by this prospectus. We may also designate agents to solicit offers to purchase the securities from time to time, and may enter into arrangements for "at-the-market," equity line or similar transactions. We will name in a prospectus supplement any underwriter or agent involved in the offer or sale of the securities.

        If we utilize a dealer in the sale of the securities being offered by this prospectus, we will sell the securities to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale.

        If we utilize an underwriter in the sale of the securities being offered by this prospectus, we will execute an underwriting agreement with the underwriter at the time of sale, and we will provide the name of any underwriter in the prospectus supplement which the underwriter will use to make resales

prospectus and applicable prospectus supplements in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a specificpart, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that describes the terms of the series of preferred stock under this prospectus, we will describeare offering before the termsissuance of thethat series of preferred stock in the prospectus supplement for such offering and will file a copy of the restated certificate establishing the terms of the preferred stock with the SEC. To the extent required, thisstock. This description will include:

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the title and stated value;



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amendment to our certificate of incorporation if the amendment would change the par value or, unless the certificate of incorporation provided otherwise, the number of authorized shares of the class or change the powers, preferences or special rights of the class or series so as to adversely affect the class or series, as the case may be. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation.

Anti-Takeover Provisions

Section 203 of the Delaware General Corporation Law

We are subject to Section 203 of the DGCL, which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with the following exceptions:

In general, Section 203 defines a “business combination” to include the following:

In general, Section 203 defines an “interested stockholder” as an entity or person who, together with the person’s affiliates and associates, beneficially owns, or within three years prior to the time of determination of interested stockholder status did own, 15% or more of the outstanding voting stock of the corporation.

Staggered Board

Our restated certificate and by-laws divide our board of directors into three classes with staggered three year terms. In addition, our restated certificate and by-laws provide that directors may be removed only for cause and only by the affirmative vote of the holders of 75% of our shares of capital stock present in person or by proxy and entitled to vote. Under our restated certificate and by-laws, any vacancy on our board of directors, including a vacancy resulting from an enlargement of our board of directors, may be filled only by vote of a majority of our

directors then in office. Furthermore, our restated certificate provides that the authorized number of directors may be changed only by the resolution of our board of directors, subject to the rights of any holders of preferred stock to elect directors. The classification of our board of directors and the limitations on the ability of our stockholders to remove directors, change the authorized number of directors and fill vacancies could make it more difficult for a third party to acquire, or discourage a third party from seeking to acquire, control of us.

Authorized but Unissued Shares

The authorized but unissued shares of common stock and preferred stock are available for future issuance without stockholder approval, subject to any limitations imposed by the listing standards of any exchange on which our shares are listed. These additional shares may be used for a variety of corporate finance transactions, acquisitions and employee benefit plans. The existence of authorized but unissued and unreserved common stock and preferred stock could make more difficult or discourage an attempt to obtain control of us by means of a proxy contest, tender offer, merger or otherwise.

Special Meeting of Stockholders; Advance Notice Requirements for Stockholder Proposals and Director Nominations; Stockholder Action

Our restated certificate provides that we will indemnify each person who was or is a party or threatened to be made a party to any threatened, pending or completed action, suit or proceeding, other than an action by or in the right of us, by reason of the fact that he or she is or was, or has agreed to become, a director or officer, or is or was serving, or has agreed to serve, at our request as a director, officer, partner, employee or trustee of, or in a similar capacity with, another corporation, partnership, joint venture, trust or other enterprise (all such persons being referred to as an “Indemnitee”), or by reason of any action alleged to have been taken or omitted in such capacity, against all expenses, including attorneys’ fees, judgments, fines and amounts paid in settlement actually and reasonably incurred in connection with such action, suit or proceeding and any appeal therefrom, if such Indemnitee acted in good faith and in a manner he or she reasonably believed to be in, or not opposed to, our best interests, and, with respect to any criminal action or proceeding, he or she had no reasonable cause to believe his or her conduct was unlawful.

Super Majority Voting

The DGCL provides generally that the affirmative vote of a majority of the shares entitled to vote on any matter is required to amend a corporation’s certificate of incorporation or by-laws, unless a corporation’s certificate of incorporation or by-laws, as the case may be, require a greater percentage. Our by-laws may be amended or repealed by a majority vote of our board of directors or the affirmative vote of the holders of at least 75% of the votes that all of our stockholders would be entitled to cast in any election of directors. In addition, the affirmative vote of the holders of at least 75% of the votes that all of our stockholders would be entitled to cast in any election of directors is required to amend or repeal or to adopt any provisions inconsistent with certain of the provisions of our restated certificate.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A., with offices at 250 Royall Street, Canton, Massachusetts 02021. The transfer agent for any series of preferred stock will be set forth in the applicable prospectus supplement.

DESCRIPTION OF DEBT SECURITIES

        The following description, together with the additional information we include in any applicable prospectus supplements, summarizes the material terms and provisions of the debt securities that we may offer under this prospectus.prospectus will be named and described in the prospectus supplement for that series.

Listing on Nasdaq

Our common stock is listed on the Nasdaq Capital Market under the symbol “TPST.”

DESCRIPTION OF DEBT SECURITIES

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any future debt securities that we may offer pursuant tounder this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. If we so indicate in a prospectus supplement, theThe terms of any debt securities offered under sucha prospectus supplement may differ from the terms described below. Unless the context requires otherwise, whenever we describe below, andrefer to the extentindenture, we also are referring to any supplemental indentures that specify the terms set forth inof a prospectus supplement differ from the terms described below, the terms set forth in the prospectus supplement shall control.particular series of debt securities.

        We may sell from time to time, in one or more offerings under this prospectus, debt securities, which may be senior or subordinated. We will issue any such seniorthe debt securities under a seniorthe indenture that we will enter into with athe trustee to be named in the senior indenture. WeThe indenture will issue any such subordinated debt securitiesbe qualified under a subordinated indenture, which we will enter into with a trustee to be named in the subordinated indenture.Trust Indenture Act of 1939, as amended, or the Trust Indenture Act. We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of these documentsdebt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part. We use the term "indentures" to refer to either the senior indenturepart or the subordinated indenture, as applicable. The indentures will be qualified underincorporated by reference from reports that we file with the Trust Indenture Act of 1939, as in effect on the date of the indenture. We use the term "debenture trustee" to refer to either the trustee under the senior indenture or the trustee under the subordinated indenture, as applicable.

Conversion or Exchange Rights

We will set forth in the applicable prospectus supplement the terms if any, on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale; No ProtectionSale

Unless we provide otherwise in Eventthe prospectus supplement applicable to a particular series of a Change of Control or Highly Leveraged Transaction

        The indentures dodebt securities, the indenture will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of allour assets as an entirety or substantially all of our assets.as an entirety. However, any successor to or acquirer of such assets (other than a subsidiary of ours) must assume all of our obligations under the indenturesindenture or the debt securities, as appropriate.

Events of Default under the Indenture

Unless we stateprovide otherwise in the applicable prospectus supplement theapplicable to a particular series of debt securities, will not contain any provisions that may afford holders of the debt securities protection in the event we have a change of control or in the event of a highly leveraged transaction (whether or not such transaction results in a change of control), which could adversely affect holders of debt securities.

Events of Default Under the Indenture

        The following are events of default under the indenturesindenture with respect to any series of debt securities that we may issue:

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if we fail to pay any installment of interest on any series of debt securities, as and when the same shall become due and our failurepayable, and such default continues for a period of 90 days anddays; provided, however, that a valid extension of an interest payment period by us in accordance with the timeterms of any indenture supplemental thereto shall not constitute a default in the payment of interest for payment has not been extended or deferred;



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this purpose;

Additionally, except in the principal (or, ifcase of a default in the debt securities of that series are discount securities, that portionpayment of the principal amountof (or premium, if any) or interest on any security, the trustee shall be protected in withholding such notice if and so long as may be specifiedthe officers of the trustee in good faith determine that the withholding of such notice is in the terms of that series) of and premium and accrued and unpaid interest if any, on all debt securities of that series. Before a judgment or decree for payment of the money due has been obtained with respect to debt securities of any series, theholders

The holders of a majority in principal amount of the outstanding debt securities of thatan affected series (or, at a meetingmay waive any default or event of holders of suchdefault with respect to the series at which a quorum is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) may rescind and annul the acceleration if allits consequences, except defaults or events of default other than the non-paymentregarding payment of accelerated principal, premium, if any, and interest, if any, with respect to debt securities of that series, have been cured or waived as provided in the applicable indenture (including payments or deposits in respect of principal, premium or interest, that had become due other than as a resultunless we have cured the default or event of such acceleration). We refer you todefault in accordance with the prospectus supplement relating to any series of debt securities that are discount securities forindenture. Any waiver shall cure the particular provisions relating to acceleration of a portion of the principal amount of such discount securities upon the occurrence of andefault or event of default.

Subject to the terms of the indentures,indenture, if an event of default under an indenture shall occur and be continuing, the debenture trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the debenture trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the debenture trustee, or exercising any trust or power conferred on the debenture trustee, with respect to the debt securities of that series, provided that:

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the direction so given by the holder is not in conflict with any law or the applicable indenture; and



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In addition, under the indentures,indenture, the rights of holders of a series of debt securities may be changed by us and the debenture trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series (or, at a meeting of holders of such series at which a quorum is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) that is affected. However, unless we provide otherwise in the debentureprospectus supplement applicable to a particular series of debt securities, we and the trustee and we may make the following changes only with the consent of each holder of any outstanding debt securities affected:

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extending the fixed maturity of the seriesany debt securities of debt securities;



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any series;

Form, Exchange and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we provide otherwise specify in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indentures provideindenture provides that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company, or DTC, or another depositary named by us and identified in athe applicable prospectus supplement with respect to that series. To the extent the debt securities of a series are issued in global form and as book-entry, a description of terms relating to any book-entry securities will be set forth in the applicable prospectus supplement.

At the option of the holder, subject to the terms of the indenturesindenture and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indenturesindenture and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, or in the applicable indenture, we will makeimpose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

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issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or



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We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will we make interest payments by check whichthat we will mail to the holder.holder or by wire transfer to certain holders. Unless we otherwise indicate in athe applicable prospectus supplement, we will designate the corporate trust office of the debenture trustee in the City of New York as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the debenture trustee for the payment of the principal of or any premium or interest on any debt securities whichthat remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

Governing Law

The indenturesindenture and the debt securities will be governed by and construed in accordance with the internal laws of the State of New York, except to the extent that the Trust Indenture Act is applicable.

Subordination of Subordinated Debt Securities

DESCRIPTION OF WARRANTS

The following description, together with the extent described in a prospectus supplement. The subordinated indenture does not limit the amount of senior indebtednessadditional information we may incur. It also does not limit us from issuinginclude in any other secured or unsecured debt.

DESCRIPTION OF WARRANTS

General

        We may issue warrants to purchase shares of our common stock, preferred stock and/or debt securities in one or more series together with other securities or separately, as described in the applicable prospectus supplement. Below is a description of certain generalsupplements and free writing prospectuses, summarizes the material terms and provisions of the warrants that we may offer. Particular termsoffer under this prospectus, which may consist of the warrants will be described in the warrant agreements and the prospectus supplement relating to the warrants.

        The applicable prospectus supplement will contain, where applicable, the following terms of and other information relating to the warrants:

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the specific designation and aggregate number of, and the price at which we will issue, the warrants;



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the currency or currency units in which the offering price, if any, and the exercise price are payable;



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the designation, amount and terms of the securities purchasable upon exercise of the warrants;



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if applicable, the exercise price for shares of our common stock and the number of shares of common stock to be received upon exercise of the warrants;

Before exercising their warrants, holders of warrants will not have any of the units orrights of holders of the securities comprisingpurchasable upon such exercise, including:

 The provisions described

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify 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 anythe applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information, 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 in connection with the exercise of the warrant.

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 described under "Descriptionall or part of Common Stock," "Descriptionthe exercise price for warrants.

Enforceability of Preferred Stock," "Description of Debt Securities," "DescriptionRights by Holders of Warrants" "Description

Each warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of Rights"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 "Descriptionreceive the securities purchasable upon exercise of, Purchase Contracts"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 apply to eachissue under a separate agreement. We may enter into unit as applicable, and to any common stock, preferred stock, debt security, warrant, rightagreements with a unit agent. Each unit agent will be a bank or purchase contract included in each unit, as applicable.

Unit Agent

        Thetrust company that we select. We will indicate the name and address of the unit agent for any units we offer will be set forth in the applicable prospectus supplement.supplement relating to a particular series of units.

IssuanceThe following description, together with the additional information included in Seriesany 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:

 We may issue

Enforceability of Rights by Holders of Units

        EachTo 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.

DESCRIPTION OF RIGHTS

We may issue rights to purchase common stock, preferred stock, debt securities or units. Rights may be issued independently or together with other securities and may or may not be transferable by the person purchasing or receiving the rights. In connection with any "interested stockholder"rights offering to our stockholders, we may enter into a standby underwriting, backstop or other arrangement with one or more underwriters or other persons pursuant to which such underwriters or other persons would purchase any offered securities remaining unsubscribed for three yearsafter such rights offering. In connection with a rights offering to our stockholders, we would distribute certificates evidencing the rights and a prospectus supplement to our stockholders on or about the record date that we set for receiving rights in such rights offering.

The applicable prospectus supplement will describe the following terms of any rights we may issue, including some or all of the following:

 Our restated certificate of incorporation provides that we will indemnify each person who was or is a party or threatened to be made a party to any threatened, pending or completed action, suit or proceeding, other than an action by or in the right of us, by reason of the fact that he or she is or was, or has agreed to become, a director or officer, or is or was serving, or has agreed to serve, at our request as a director, officer, partner, employee or trustee of, or in a similar capacity with, another corporation, partnership, joint venture, trust or other enterprise (all such persons being referred to as an "Indemnitee"), or by reason of any action alleged to have been taken or omitted in such capacity, against all expenses, including attorneys' fees, judgments, fines and amounts paid in settlement actually and reasonably incurred in connection with such action, suit or proceeding and any appeal therefrom, if

Exercise of Rights

Each right will entitle the holder to purchase for cash or settlementother consideration such shares of stock or principal amount of securities at the subscription price as shall in each case be set forth in, or be determinable as set forth in, the prospectus supplement relating to the rights offered thereby. Rights may be exercised as set forth in the applicable prospectus supplement beginning on the date specified therein and continuing until the close of business on the expiration date set forth in the prospectus supplement relating to the rights offered thereby. After the close of business on the expiration date, unexercised rights will become void.

Upon receipt of payment and a subscription certificate properly completed and duly executed at the corporate trust office of the subscription agent or any other office indicated in the prospectus supplement, we will, as soon as practicable, forward the securities purchasable upon such exercise. If less than all of the rights represented by such subscription certificate are exercised, a new subscription certificate will be issued for the remaining rights. If we so indicate in the applicable prospectus supplement, holders of the rights may surrender securities as all or part of the exercise price for rights.

We may determine to offer any unsubscribed offered securities directly to stockholders, persons other than stockholders, to or through agents, underwriters or dealers or through a combination of such an actionmethods, including pursuant to standby underwriting, backstop or suitother arrangements, as set forth in the applicable prospectus supplement.

Prior to exercising their rights, holders of rights will not have any of the rights of holders of the securities purchasable upon subscription, including, in the case of rights to purchase common stock or preferred stock, the right to receive dividends, if suchany, or payments upon our liquidation, dissolution or winding up or to exercise any voting rights or, in the case of rights to purchase debt securities, the right to receive principal, premium, if any, or interest payments, on the debt securities purchasable upon exercise or to enforce covenants in the applicable indenture.

LEGAL OWNERSHIP OF SECURITIES

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee or depositary or warrant agent maintain for this purpose as the “holders” of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as “indirect holders” of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

Book-Entry Holders

We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary’s book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person acted in good faithwhose name a security is registered is recognized as the holder of that security. Global securities will be registered in the name of the depositary or its participants. Consequently, for global securities, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a mannerglobal security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary’s book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not legal holders, of the securities.

Street Name Holders

We may terminate a global security or issue securities that are not issued in global form. In these cases, investors may choose to hold their securities in their own names or in “street name.” Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she reasonably believedmaintains at that institution.

For securities held in street name, we or any applicable trustee or depositary will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we or any such trustee or depositary will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be in,indirect holders, not legal holders, of those securities.

Legal Holders

Our obligations, as well as the obligations of any applicable trustee or not opposed to, the best interests of the corporation, except that no indemnification shall be provided if such person shall have been adjudged to be liable to the corporation, unless andthird party employed by us or a trustee, run only to the extentlegal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the holder, we have no further responsibility for the payment or notice even if that holder is required, under agreements with its participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of an indenture, or for other purposes. In such an event, we would seek approval only from the legal holders, and not the indirect holders, of the securities. Whether and how the legal holders contact the indirect holders is up to the legal holders.

Special Considerations for Indirect Holders

If you hold securities through a bank, broker or other financial institution, either in book-entry form because the securities are represented by one or more global securities or in street name, you should check with your own institution to find out:

Global Securities

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we issue to, deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, The Depository Trust Company, New York, New York, known as DTC, will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under “—Special Situations When a Global Security Will Be Terminated.” As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and legal holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a legal holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the Delaware Chancery Courtsecurity will be issued as a global security, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the courtsecurities may no longer be held through any book-entry clearing system.

Special Considerations for Global Securities

As an indirect holder, an investor’s rights relating to a global security will be governed by the account rules of the investor’s financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only as global securities, an investor should be aware of the following:

There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.

Special Situations When a Global Security Will Be Terminated

In a few special situations described below, a global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own names, so that they will be direct holders. We have described the rights of holders and street name investors above.

A global security will terminate when the following special situations occur:

The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the prospectus supplement. When a global security terminates, the depositary, and neither we nor any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

PLAN OF DISTRIBUTION

We may sell the securities from time to time pursuant to underwritten public offerings, negotiated transactions, block trades or a combination of these methods. We may sell the securities to or through underwriters or dealers, through agents, or directly to one or more purchasers. We may distribute securities from time to time in one or more transactions:

We may also sell equity securities covered by this registration statement in an “at the market” offering as defined in Rule 415(a)(4) under the Securities Act. Such offering may be made into an existing trading market for such securities in transactions at other than a fixed price on or through the facilities of the Nasdaq Capital Market or any other securities exchange or quotation or trading service on which such securities may be listed, quoted or traded at the time of sale.

Such at the market offerings, if any, may be conducted by underwriters acting as principal or agent.

A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you) will describe the terms of the offering of the securities, including, to the extent applicable:

        Pursuant to Section 102(b)(7)Only underwriters named in the prospectus supplement are underwriters of the Delaware General Corporation Law, Article Ninthsecurities offered by the prospectus supplement.

If underwriters are used in the sale, they will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of our restated certificate of incorporation eliminates the liability of a director to us or our stockholders for monetary damages for such a breach of fiduciary duty as a director, except for liabilities arising:

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from any breachsale. The obligations of the director's duty of loyaltyunderwriters to uspurchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or our stockholders;



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from acts or omissions not in good faith or which involve intentional misconduct orby underwriters without a knowing violation of law;

We have entered into indemnification agreements with our directorsmay authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and certain officers, in addition to the indemnification provided in our restated certificate of incorporation and our amended and restated bylaws, and intend to enter into indemnification agreements with any new directors and executive officersdelivery on a specified date in the future. We have purchasedwill describe the conditions to these contracts and intendthe commissions we must pay for solicitation of these contracts in the prospectus supplement.

We may provide agents and underwriters with indemnification against civil liabilities related to maintain insurance on behalf of any person who is or was a director or officer against any loss arising from any claim asserted against him or her and incurred by him or her in any such capacity, subject to certain exclusions.

        The foregoing discussion of our restated certificate of incorporation, amended and restated bylaws, indemnification agreements, indemnity agreement, and Delaware law is not intended to be exhaustive and is qualified in its entirety by such restated certificate of incorporation, amended and restated bylaws, indemnification agreements, indemnity agreement, or law.

        Insofar as indemnification forthis offering, including liabilities arising under the Securities Act, or contribution with respect to payments that the agents or underwriters may be permittedmake with respect to our directors, officersthese liabilities. Agents and controlling persons pursuant to the foregoing provisions,underwriters may engage in transactions with, or otherwise, we have been advised thatperform services for, us in the opinionordinary course of business.

All securities we offer, other than common stock, will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the SEC such indemnification is against public policytrading markets for any securities.

Any underwriter may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids. Overallotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as expressedthe stabilizing bids do not exceed a specified maximum. Short covering transactions involve purchases of the securities in the Securities Act andopen market after the distribution is therefore, unenforceable.

LEGAL MATTERS

        Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., Boston, Massachusetts, will pass uponcompleted to cover short positions. Penalty bids permit the validity ofunderwriters to reclaim a selling concession from a dealer when the issuancesecurities originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time. These transactions may be effected on any exchange or over-the-counter market or otherwise.

Any underwriters who are qualified market makers on the Nasdaq Capital Market may engage in passive market making transactions in the securities on the Nasdaq Capital Market in accordance with Rule 103 of Regulation M, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the securities. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the securities at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.

LEGAL MATTERS

Unless otherwise indicated in the applicable prospectus supplement, certain legal matters in connection with the offering and the validity of the securities offered by this prospectus.prospectus, and any supplement thereto, will be passed upon by Sidley Austin LLP, San Francisco, California. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

Ernst & Young LLP, independent registered public accounting firm, has audited ourthe consolidated financial statements of Millendo Therapeutics, Inc. included in ourits Annual Report on Form 10-K for the year ended December 31, 2015, and the effectiveness of our internal control over financial reporting as of December 31, 2015,2020, as set forth in their reports,report, which areis incorporated by reference in this prospectus and elsewhere in the registration statement. OurThese financial statements are incorporated by reference in reliance on Ernst & Young LLP'sLLP’s report, given on their authority as experts in accounting and auditing.

The financial statements of Tempestx, Inc. (formerly Tempest Therapeutics, Inc.) as of and for the years end December 31, 2020 and December 31, 2019 , incorporated by reference in this Prospectus from Tempest Therapeutics, Inc.’s Current Report on Form 8-K filed on July 16, 2021, have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report which is incorporated by reference (which report expresses an unqualified opinion on the financial statements and includes an explanatory paragraph referring to substantial doubt regarding Tempestx, Inc.’s ability to continue as a going concern). Such financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement we filed with the SEC. This prospectus does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the securities we are offering under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement. You should rely only on the information contained in this prospectus or incorporated by reference in this prospectus. We have not authorized anyone else to provide you with different information. We are subject tonot making an offer of these securities in any state where the reporting requirementsoffer is not permitted. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front page of this prospectus, regardless of the Securities Exchange Acttime of 1934, as amended, anddelivery of this prospectus or any sale of the securities offered by this prospectus.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy these reports, proxy statements and other information at the SEC's public reference facilities at 100 F Street, N.E., Room 1580, Washington, D.C. 20549. You can request copies of these documents by writing to the SEC and paying a fee for the copying cost. Please call the SEC at 1-800-SEC-0330 for more information about the operation of the public reference facilities.Our SEC filings are also available to the public over the Internet at the SEC's web siteSEC’s website athttp://www.sec.gov. This prospectus is only partwww.sec.gov.

Copies of a registration statement on Form S-3 that we havecertain information filed by us with the SEC under the Securities Act of 1933, as amended, and therefore omits certain informationare also available on our website at www.tempesttx.com. Information contained in the registration statement. We have also filed exhibits and schedules with the registration statement that are excluded fromor accessible through our website does not constitute a part of this prospectus and you should refer to the applicable exhibit or schedule for a complete description of any statement referring to any contract or other document. You may inspect a copy of the registration statement, including the exhibits and schedules, without charge, at the public reference room or obtain a copy from the SEC upon payment of the fees prescribed by the SEC.

        We also maintain a website atwww.ovascience.com, through which you can access our SEC filings. The information set forth on our website is not part ofincorporated by reference in this prospectus.

INCORPORATION OF DOCUMENTSCERTAIN INFORMATION BY REFERENCE

The SEC allows us to "incorporate“incorporate by reference"reference” information into this prospectus, which means that we file with them. Incorporation by reference allows us tocan disclose important information to you by referring you to those other documents. The information incorporated by reference is an important part of this prospectus, and information that we file lateranother document filed separately with the SEC. The SEC will automatically update and supersede this information. We filed a registration statement on Form S-3 under the Securities Act of 1933, as amended, with the SEC with respect to the securities we may offer pursuant to this prospectus. This prospectus omits certain information contained in the registration statement, as permitted by the SEC. You should refer to the registration statement, including the exhibits,file number for further information about us and the securities we may offer pursuant to this prospectus. Statements in this prospectus regarding the provisions of certain documents filed with, or incorporated by reference in, the registration statement are not necessarily complete and each statement is qualified in all respects by that reference. Copies of all or any part of the registration statement, including the documents incorporated by reference or the exhibits, may be obtained upon payment of the prescribed rates at the offices of the SEC listed above in "Where You Can Find More Information."this prospectus is 001-35890. The documents we are incorporatingincorporated by reference are:into this prospectus contain important information that you should read about us.

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our

The following documents are incorporated by reference into this document:

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Our Annual Report on Form 10-K and 10-K/A for the fiscal year ended December 31, 2020;

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Our Quarterly Report on Form 10-Q for the quarter ended March 31, 2021;

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Our Current Reports on Form 8-K and Form 8-K/A filed with the SEC on January 5, 2021, January 28, 2021, March 29, 2021, June  11, 2021, June 23, 2021, June 28, 2021 (other than the information furnished pursuant to Item 7.01 and Exhibit 99.1), July  1, 2021, July 7, 2021, July  12, 2021 and July 16, 2021; and

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The description of our common stock set forth in the registration statement on Form 8-A registering our common stock under Section 12 of the Exchange Act, which was filed with the SEC on April 25, 2013, including any amendments or reports filed for purposes of updating such description.

We also incorporate by reference into this prospectus all documents (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on Form 10-K for the fiscal year ended December 31, 2015such form that weare related to such items) that are filed by us with the SEC on February 26, 2016;



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the portions of our definitive proxy statement on Schedule 14A filed on April 18, 2016 that are deemed "filed" with the SEC under the Exchange Act;



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our Quarterly Reports on Form 10-Q for the fiscal quarters ended March 31, 2016, June 30, 2016 and September 30, 2016 that we filed with the SEC on May 5, 2016, August 4, 2016 and November 3, 2016, respectively;



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our Current Reports on Form 8-K that we filed with the SEC on January 6, 2016, March 31, 2016, May 25, 2016, May 26, 2016, June 3, 2016, July 1, 2016 and September 6, 2016 (except for the information furnished under Items 2.02 or 7.01 and the exhibits furnished thereto);



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the description of our common stock contained in our Registration Statement on Form 8-A filed on April 25, 2013, including any amendment or report filed for the purpose of updating such description; and



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all reports and other documents subsequently filed by us pursuant to Sections 13(a), 13(c), 14 andor 15(d) of the Exchange Act after the date of this prospectus and prior to the termination or completion of the offering of securities under this prospectus shall be deemed to be incorporated by reference in this prospectus and to be a part hereof from the date of filing such reports and other documents.

        The SEC file number for each of the documents listed above is 001-35890.

        In addition, all reports and other documents filed by us pursuant to the Exchange Act(i) after the date of the initial filing of the registration statement of which this prospectus forms a part and prior to effectiveness of the registration statement, shall be deemedor (ii) after the date of this prospectus but prior to bethe termination of the offering. These documents include periodic reports, such as Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, as well as proxy statements.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, without charge upon written or oral request, a copy of any or all of the documents that are incorporated by reference into this prospectus.prospectus but not delivered with the prospectus, including exhibits that are specifically incorporated by reference into such documents. You should direct any requests for documents to Tempest Therapeutics, Inc., Attn: Investor Relations, 7000 Shoreline Court; Suite 275 South San Francisco, CA 94080.

Any statement contained in this prospectus or 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 supplement to this prospectus, or document that is deemed to be incorporated by reference into this prospectus, modifies or supersedes thesuch statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

 You should rely only on information contained in, or incorporated by reference into, this prospectus and any prospectus supplement. We have not authorized anyone to provide you with information different from that contained in this prospectus or incorporated by reference in this prospectus. We are not making offers to sell the securities in any jurisdiction in which such an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make such offer or solicitation.

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OVASCIENCE, INC.

$175,000,000

Common Stock
Preferred Stock
Debt Securities
Warrants
Rights Purchase
Contract Units