424B7

The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement is part of an effective registration statement filed with the Securities and Exchange Commission. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and neither we nor the selling stockholders are soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

The selling stockholders identified in this prospectus supplement are offering 8,000,000 shares of Class A common stock, or common stock. We will not receive any proceeds from the sale of our common stock by the selling stockholders.

Our common stock is listed on the NASDAQ Global Select Market, or the NASDAQ, under the symbol “INCR.” The last reported sale price of our common stock on NASDAQ on April 29, 2016, was $48.13 per share.

Investing in our common stock involves risks. See “Risk Factors” beginning on page S-7 of this prospectus supplement, beginning on page 3 of the accompanying prospectus, and in our Annual Report on Form 10-K for the fiscal year ended December 31, 2015 (which is incorporated by reference herein) to read about factors you should consider before making a decision to invest in our common stock.

The underwriter has agreed to purchase the shares of our common stock from the selling stockholders at a price of $ per share, which will result in $ of proceeds to the selling stockholders before expenses. The underwriter proposes to offer the shares of common stock from time to time for sale in one or more transactions on the NASDAQ, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. See “Underwriting.”

Neither the Securities and Exchange Commission nor any other regulatory body has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus supplement. Any representation to the contrary is a criminal offense.

The underwriter expects to deliver the shares against payment in New York, New York on , 2016.

We have not authorized anyone to provide any information or to make any representations other than those contained or incorporated by reference herein or in any free writing prospectuses we have prepared. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus supplement is an offer to sell only the shares offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. The information contained in this prospectus supplement is current only as of its date. Our business, financial condition, results of operation and prospects may have changed since that date.

On December 1, 2015, we filed with the Securities and Exchange Commission, or SEC, a registration statement on Form S-3 utilizing a shelf registration process relating to the securities described in this prospectus supplement, which was automatically declared effective upon filing.

This prospectus supplement describes the specific terms of an offering of our common stock and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into the accompanying prospectus. The second part, the accompanying prospectus, provides more general information. If the information in this prospectus supplement is inconsistent with the accompanying prospectus or any document incorporated by reference therein filed prior to the date of this prospectus supplement, you should rely on the information in this prospectus supplement.

It is important for you to read and consider all of the information contained in this prospectus supplement and the accompanying prospectus in making your investment decision. We include cross-references in this prospectus supplement and the accompanying prospectus to captions in these materials where you can find additional related discussions. The table of contents in this prospectus supplement provides the pages on which these captions are located. You should read both this prospectus supplement and the accompanying prospectus, together with the additional information described in the sections entitled “Where You Can Find More Information” and “Incorporation of Documents by Reference” of this prospectus supplement, before investing in our common stock.

The selling stockholders are offering to sell, and seeking offers to buy, shares of common stock only in jurisdictions where offers and sales are permitted. The distribution of this prospectus supplement and the accompanying 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 supplement and the accompanying prospectus must inform themselves about, and observe any restrictions relating to, the offering of the common stock and the distribution of this prospectus supplement and the accompanying prospectus outside the United States. This prospectus supplement and the accompanying 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 supplement and the accompanying prospectus by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights information contained elsewhere in this prospectus supplement or incorporated by reference into this prospectus supplement and the accompanying prospectus. This summary is not complete and does not contain all of the information that you should consider before investing in our common stock. Before investing in our common stock, you should carefully read the entire prospectus supplement, the accompanying prospectus, any applicable free writing prospectus we file with the SEC and the information incorporated herein by reference, including the financial data and related notes and the sections entitled “Risk Factors.” Unless the context requires otherwise, references to “our company,” “we,” “us” and “our” refer to INC Research Holdings, Inc. and its direct and indirect subsidiaries; references to “INC Holdings” refer to INC Research Holdings, Inc.; and references to “INC” refer to INC Research, LLC, our wholly-owned subsidiary. Unless the context otherwise requires, references to “common stock” refer to our Class A common stock. References to GAAP are to the generally accepted accounting principles of the United States.

Overview

We are a leading global Contract Research Organization based on revenues, and are exclusively focused on Phase I to Phase IV clinical development services for the biopharmaceutical and medical device industries. We provide our customers highly differentiated therapeutic alignment and expertise, with a particular strength in central nervous system, oncology and other complex diseases. We consistently and predictably deliver clinical development services in a complex environment and offer a proprietary, operational approach to clinical trials through our Trusted Process ^® methodology. Our service offerings focus on optimizing the development of, and therefore, the commercial potential for, our customers’ new biopharmaceutical compounds, enhancing returns on their research and development investments and reducing their overhead by offering an attractive variable cost alternative to fixed cost, in-house resources.

Our Sponsors

Following the closing of this offering, affiliates of Avista Capital Partners II, L.P., or Avista, and affiliates of Teachers Private Capital, or Teachers, the private investment arm of Ontario Teachers’ Pension Plan Board, or OTPP, together will own approximately 24.1% of our outstanding common stock. We expect that following this offering Avista will own approximately 12.3% of our outstanding common stock, and Teachers will own approximately 11.8% of our outstanding common stock. The common stock is entitled to one vote per share. As a result, Avista and Teachers (each, a “Sponsor” and together, the “Sponsors”) will be able to exert significant voting influence over fundamental and significant corporate matters and transactions. See “Risk Factors—Risks Related to Our Common Stock and this Offering—Our Sponsors have significant influence over our company, and their interests may be different from or conflict with those of our other stockholders.” See also “Principal and Selling Stockholders.” As a result of their sale of common stock in December 2015, the Sponsors own less than 50% of the total voting power of our common stock, so we are no longer a “controlled company” within the meaning of NASDAQ listing standards. As such, we are currently in a phase-in period and we may continue to rely on exemptions from certain corporate governance requirements. See “Risk Factors—Risks Related to Our Common Stock and this Offering—Although we are no longer a “controlled company” within the meaning of the NASDAQ rules, we are relying on exemptions from certain corporate governance requirements during transition periods of up to one year.”

Our Structure

The diagram below reflects a simplified overview of our organizational structure following this offering:

LOGO

Corporate Information

We are a Delaware corporation and were incorporated on August 13, 2010. Our principal executive office is located at 3201 Beechleaf Court, Suite 600, Raleigh, North Carolina 27604-1547. Our telephone number at our principal executive office is (919) 876-9300. Our corporate website is www.incresearch.com. The information on our corporate website is not part of, and is not incorporated by reference into, this prospectus supplement.

THE OFFERING

Common stock offered by the selling stockholders

8,000,000 shares.

Common stock to be outstanding after this offering

54,221,660 shares.

Use of proceeds

We will not receive any of the proceeds from the sale of shares of common stock by the selling stockholders.

Dividend policy

We do not anticipate paying any dividends on our common stock in the foreseeable future; however, we may change this policy in the future. See “Dividend Policy.”

Risk factors

Investing in our common stock involves a high degree of risk. See “Risk Factors” beginning on page S-6 of this prospectus supplement, in the accompanying prospectus and the documents incorporated by reference for a discussion of factors you should consider carefully before investing in our common stock.

NASDAQ trading symbol

“INCR.”

Unless otherwise indicated, the number of shares of our common stock outstanding after this offering excludes:

•

1,246,470 shares of our common stock issuable upon exercise of outstanding stock options as of March 31, 2016 with a weighted average exercise price of $10.56 per share;

•

1,822,531 shares of our common stock reserved for the future issuance, as of March 31, 2016, under our 2014 Equity Incentive Plan, or the 2014 Plan; and

•

607,333 shares of nonvested restricted stock units outstanding as of March 31, 2016.

Investing in our common stock involves a high degree of risk. You should consider carefully the risks and uncertainties described below together with the other information included in this prospectus supplement, the accompanying prospectus and incorporated by reference herein, before deciding to purchase our common stock. In addition, you should carefully consider, among other things, the section entitled “Risk Factors” beginning on page 19 of our Annual Report on Form 10-K for the fiscal year ended December 31, 2015 and other information in our consolidated financial statements, all of which are incorporated by reference into this prospectus supplement. The risks described below and incorporated herein by reference are those which we believe are the material risks that we face. The occurrence of any of the following risks may materially and adversely affect our business, financial condition, results of operations, cash flows, reputation and future prospects. In this event, the market price of our common stock could decline, and you could lose part or all of your investment.

Our stock price might fluctuate significantly, which could cause the value of your investment in our common stock to decline, and you might not be able to resell your shares at a price at or above the public offering price.

Since our initial public offering, or IPO, in November 2014, the price of our common stock, as reported by NASDAQ, has ranged from a low of $19.61 on November 7, 2014 to a high of $57.11 on April 18, 2016. In addition, securities markets worldwide have experienced, and are likely to continue to experience, significant price and volume fluctuations. This market volatility, as well as general economic, market or political conditions, could reduce the market price of our common stock regardless of our results of operations. The public market for our common stock continues to be relatively new, and its trading price is likely to be volatile and subject to significant price fluctuations in response to many factors. For example, we currently give annual financial guidance. That guidance, any changes in it and any failure to meet it, impact the market for our stock. In addition, securities analysts publish annual and quarterly financial estimates and ratings with respect to our company. Analyst estimates of our quarterly results might not necessarily reflect our expectations of the quarterly financial results. We do not give quarterly guidance because quarterly results can be particularly volatile due to the variability in the timing of revenue recognition from change orders and the timing of expense recognition. Changes in quarterly results, analyst estimates of those results or our failure to meet those estimates for any reason can impact the price of and market for our common stock. Other factors that impact the market for our stock include:

These and other factors may cause the market price and demand for shares of our common stock to fluctuate substantially, which may otherwise negatively affect the liquidity of our common stock. In that event, the price of our common stock would likely decrease. In the past, when the market price of a stock has been volatile, security holders have often instituted class action litigation against the company that issued the stock. If we become involved in this type of litigation, regardless of the outcome, we could incur substantial legal costs and our management’s attention could be diverted from the operation of our business, which could have a material adverse effect on our business, financial condition, results of operations and cash flows.

We do not anticipate that we will pay any dividends to holders of our common stock for the foreseeable future. Any payment of cash dividends will be at the discretion of our Board and will depend on our financial condition, capital requirements, legal requirements, earnings and other factors. Our ability to pay dividends is restricted by the terms of our credit agreement and might be restricted by the terms of any indebtedness that we incur in the future. Consequently, you should not rely on dividends in order to receive a return on your investment. See “Dividend Policy.”

Future sales of our common stock in the public market, including in this offering, could cause the market price of our common stock to decrease significantly.

Sales of substantial amounts of our common stock in the public market by our stockholders may cause the market price of our common stock to decrease significantly. The perception that such sales could occur could also depress the market price of our common stock. Any such sales could also create public perception of difficulties or problems with our business and might also make it more difficult for us to raise capital through the sale of equity securities in the future at a time and price that we deem appropriate.

Upon the consummation of this offering, we will have 54,221,660 outstanding shares of common stock, of which:

As restrictions on resale expire or as shares are registered, our share price could drop significantly if the holders of these restricted or newly registered shares sell them or are perceived by the market as intending to sell them. These sales might also make it more difficult for us to raise capital through the sale of equity securities in the future at a time and at a price that we deem appropriate.

Our Sponsors have significant influence over our company, and their interests may be different from or conflict with those of our other stockholders.

After the consummation of this offering, the Sponsors will collectively beneficially own approximately 24.1% of our outstanding common stock.

As a consequence, the Sponsors continue to be able to exert a significant degree of influence over our management and affairs and matters requiring stockholder approval, including the election of directors, a merger, consolidation or sale of all or substantially all of our assets, and any other significant transaction. Additionally, the Sponsors are parties to a stockholders agreement, or the Stockholders Agreement. This Stockholders Agreement, among other things, requires such stockholders to vote in favor of certain nominees to our Board. The interests of the Sponsors might not always coincide with our interests or the interests of our other stockholders. For instance, this concentration of ownership and/or the restrictions imposed by the Stockholders Agreement may have the effect of delaying or preventing a change in control of us otherwise favored by our other stockholders and could depress our stock price.

The Sponsors each make investments in companies and may, from time to time, acquire and hold interests in businesses that compete directly or indirectly with us. Each of the Sponsors may also pursue, for its own account, acquisition opportunities that may be complementary to our business, and as a result, those acquisition opportunities might not be available to us. Our organizational documents contain provisions renouncing any interest or expectancy held by our directors affiliated with the Sponsors in certain corporate opportunities. Accordingly, the interests of the Sponsors may supersede ours, causing the Sponsors or their affiliates to compete against us or to pursue opportunities instead of us, for which we have no recourse. Such actions on the part of the Sponsors and inaction on our part could have a material adverse effect on our business, financial condition, results of operations and cash flows.

The Sponsors control four seats on our Board. Since the Sponsors could invest in entities that directly or indirectly compete with us, when conflicts arise between the interests of the Sponsors and the interests of our stockholders, these directors might not be disinterested.

Although we are no longer a “controlled company” within the meaning of the NASDAQ rules, we are relying on exemptions from certain corporate governance requirements during transition periods of up to one year.

We are no longer a “controlled company” within the meaning of the corporate governance standards contained in the NASDAQ listing standards.

Pursuant to the phase-in periods stipulated by the NASDAQ listing standards, we were required to appoint, and did appoint, a majority independent Board and majority independent compensation and nominating and corporate governance committees by March 6, 2016, which was 90 days after the date

we ceased to qualify as a controlled company. In addition, we will have to be in compliance with certain NASDAQ corporate governance requirements, including the requirements that, within one year of the date of the loss of “controlled company” status:

We intend to utilize the transition periods described above to achieve full compliance with these NASDAQ requirements. Accordingly, our stockholders do not, and during these transition periods will not, have the same protections afforded to stockholders of companies that are subject to all of the corporate governance requirements of the NASDAQ. In addition, if we are unable to comply with the heightened corporate governance requirements prior to the prescribed NASDAQ deadlines, we may incur penalties or our shares could be delisted.

We may be limited in our ability to utilize, or may not be able to utilize, net operating loss, or NOL, carryforwards to reduce our future tax liability.

As of December 31, 2015, we had U.S. federal NOL carryforwards of approximately $39.0 million and state NOL carryforwards of approximately $121.9 million, which are limited annually due to certain change in ownership provisions of Section 382 of the Internal Revenue Code of 1986, as amended, or the Code. Based on our estimates, approximately $5.1 million of our federal NOL carryforwards are subject to limitation under Section 382 of the Code and will expire unused. In addition, as a result of acquisitions and other changes in control, a portion of the U.S. NOL carryforwards are subject to limitations under Section 382. The limitations are not expected to impact the realization of the deferred tax assets associated with these NOLs. Our federal NOL carryforwards will begin to expire in 2018 and will completely expire in 2033. Our state NOL carryforwards may be used over various periods ranging from one to 20 years. See Note 9 to our consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2015 for a further discussion of our tax loss carryovers and current limitations on our ability to utilize NOLs.

Future ownership changes within the meaning of Section 382(g) of the Code may subject our tax loss carryforwards to annual limitations which would restrict our ability to use them to offset our taxable income in periods following the ownership changes. In general, the annual use limitation equals the aggregate value of our equity immediately before the ownership change multiplied by a specified tax-exempt interest rate.

Provisions of our corporate governance documents and Delaware law could make an acquisition of our company more difficult and may prevent attempts by our stockholders to replace or remove our current management, even if beneficial to our stockholders.

Provisions of our amended and restated certificate of incorporation and our amended and restated bylaws contain provisions that delay, defer or discourage transactions involving an actual or potential change in control of us or change in our management that stockholders may consider favorable, including transactions in which you might otherwise receive a premium for your shares. These provisions could also limit the price that investors might be willing to pay in the future for shares of our common stock, thereby depressing the market price of our common stock. In addition, these provisions may frustrate or prevent any attempts by our stockholders to replace or remove our current management by making it more difficult for stockholders to replace members of our Board. Because our Board is responsible for appointing the members of our management team, these provisions could in turn affect any attempt to replace current members of our management team. Among others, these provisions include, (1) our ability to issue preferred stock without stockholder approval, (2) the requirement that our stockholders may not act without a meeting, (3) requirements for advance

notification of stockholder nominations and proposals contained in our bylaws, (4) the absence of cumulative voting for our directors, (5) requirements for stockholder approval of certain business combinations and (6) the limitations on director nominations contained in our Stockholders Agreement. See “Description of Capital Stock” in the accompanying prospectus for more detail.

Additionally, Section 203 of the Delaware General Corporation Law, or the DGCL, prohibits a publicly held Delaware corporation from engaging in a business combination with an interested stockholder, generally a person which together with its affiliates owns, or within the last three years has owned, 15% of our voting stock, for a period of three years after the date of the transaction in which the person became an interested stockholder, unless the business combination is approved in a prescribed manner. The existence of the foregoing provision could also limit the price that investors might be willing to pay in the future for shares of our common stock, thereby depressing the market price of our common stock.

If securities analysts or industry analysts downgrade our shares, publish negative research or reports, or do not publish reports about our business, our share price and trading volume could decline.

The trading market for our common stock will be influenced by the research and reports that industry or securities analysts publish about us, our business and our industry. If one or more analysts adversely change their recommendation regarding our shares or our competitors’ stock, our share price would likely decline. If one or more analysts cease coverage of us or fail to regularly publish reports on us, we could lose visibility in the financial markets, which in turn could cause our share price or trading volume to decline. As a result, the market price for our common stock may decline below the public offering price and you might not be able to resell your shares of our common stock at or above the public offering price.

We are incurring increased costs and obligations as a result of being a public company.

As a relatively new public company, we are required to comply with certain additional corporate governance and financial reporting practices and policies required of a publicly traded company. As a result, we have and will continue to incur significant legal, accounting and other expenses that we were not required to incur as a privately held company, due to compliance requirements of the Exchange Act, the Sarbanes-Oxley Act of 2002, or Sarbanes-Oxley, the Dodd-Frank Act, the listing requirements of the NASDAQ , and other applicable securities rules and regulations. The Exchange Act requires, among other things, that we file annual, quarterly, and current reports with respect to our business and operating results with the SEC. We are also required to ensure that we have the ability to prepare financial statements that are fully compliant with all SEC reporting requirements on a timely basis. Compliance with these rules and regulations will increase our legal and financial compliance costs, and might make some activities more difficult, time-consuming or costly and increase demand on our systems and resources.

We might not be successful in complying with these obligations and the significant commitment of resources required for complying with them could have a material adverse effect on our business, financial condition, results of operations and cash flows.

Our internal control over financial reporting is required to meet all the standards of Section 404 of Sarbanes-Oxley, and failure to achieve and maintain effective internal control over financial reporting could have a material adverse effect on our stock price, reputation, business, financial condition, results of operations and cash flows.

Section 404 of Sarbanes-Oxley requires annual management assessments of the effectiveness of internal control over financial reporting, which started with our Annual Report on Form 10-K for the

fiscal year ended December 31, 2015. Management and our independent registered public accounting firm were first required to attest to the effectiveness of our internal control over financial reporting on an annual basis with our Annual Report on Form 10-K for the fiscal year ended December 31, 2015. The rules governing the standards that must be met to assess our internal control over financial reporting are complex and require significant documentation, testing and possible remediation of our existing controls and could result in incurring significant additional expenditures. We had to design, implement and test our internal control over financial reporting in order to comply with this obligation. The process necessary to meet these requirements was time consuming, costly, and complicated, and we will need to evaluate and refine the process on an ongoing basis. We might encounter problems or delays in completing the implementation of any required improvements and receiving a favorable attestation in connection with the attestation provided by our independent registered public accounting firm. Further, material weaknesses or significant deficiencies in our internal control over financial reporting may exist or otherwise be discovered in the future. If we are not able to meet the compliance requirements of the applicable provisions of Section 404, we will be unable to issue securities in the public markets through the use of a shelf registration statement. In addition, failure to achieve and maintain an effective internal control environment could limit our ability to report our financial results accurately and timely, result in misstatements and restatements of our consolidated financial statements, cause investors to lose confidence and have a material adverse effect on our stock price, reputation, business, financial condition, results of operations and cash flows.

We are a holding company and rely on dividends and other payments, advances and transfers of funds from our subsidiaries to meet our obligations and pay any dividends.

We have no direct operations and no significant assets other than ownership of 100% of the capital stock of our subsidiaries. Because we conduct our operations through our subsidiaries, we depend on those entities for dividends and other payments to generate the funds necessary to meet our financial obligations, and to pay any dividends with respect to our common stock. Legal and contractual restrictions in our credit agreement and other agreements which may govern future indebtedness of our subsidiaries, as well as the financial condition and operating requirements of our subsidiaries, may limit our ability to obtain cash from our subsidiaries. The earnings from, or other available assets of, our subsidiaries might not be sufficient to pay dividends or make distributions or loans to enable us to pay any dividends on our common stock or other obligations. Any of the foregoing could materially and adversely affect our business, financial condition, results of operations and cash flows.

This prospectus supplement (including the accompanying prospectus and the information incorporated or deemed to be incorporated by reference in this prospectus supplement) and any free writing prospectus that we may provide to you in connection with an offering of our common stock described in this prospectus supplement contains forward-looking statements within the meaning of Section 27A of the Securities Act. All statements other than statements of historical facts contained in this prospectus supplement, including statements regarding our future results of operations and financial position, business strategy and plans and our objectives for future operations, are forward-looking statements. The words “anticipates,” “believes,” “can,” “continue,” “could,” “estimates,” “expects,” “intends,” “seeks,” “may,” “might,” “plans,” “projects,” “should,” “would,” “targets,” “will” and the negative thereof and similar words and expressions are intended to identify forward-looking statements. Examples of forward-looking statements include, but are not limited to, statements we make regarding: (i) trends in R&D spending, outsourcing penetration rates and the incremental growth of the late-stage clinical development services market relative to the overall market; (ii) fast growing therapeutic areas and (iii) the continuous enhancement of our Trusted Process^® to deliver superior outcomes. Forward-looking statements are based largely on our current expectations and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy, short term and long term business operations and objectives, and financial needs. These forward-looking statements are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict. Moreover, we operate in a very competitive and rapidly changing environment. New risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties and assumptions, the forward-looking events and circumstances discussed in this prospectus supplement may not occur and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements. We caution you therefore against relying on these forward-looking statements.

Some of the key factors that could cause actual results to differ from our expectations include regional, national or global political, economic, business, competitive, market and regulatory conditions and the following:

The forward-looking statements included in this prospectus supplement are made only as of the date hereof. You should not rely upon forward-looking statements as predictions of future events. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances reflected in the forward-looking statements will be achieved or occur. Moreover, neither we nor any other person assumes responsibility for the accuracy and completeness of the forward-looking statements. We undertake no obligation to update publicly any forward-looking statements for

any reason after the date of this prospectus supplement to conform these statements to actual results or to changes in our expectations, except as may be required by law.

You should read this prospectus supplement with the understanding that our actual future results, levels of activity, performance and events and circumstances may be materially different from what we expect.

We will not receive any of the proceeds from the sale of shares of our common stock by selling stockholders in this offering.

Our common stock has been listed on the NASDAQ under the symbol “INCR” since November 7, 2014. Prior to that time, there was no public market for our common stock. The following table sets forth for the periods indicated the high and low sale prices of our common stock on NASDAQ.

The closing price of our common stock as of April 29, 2016 was $48.13 per share.

On April 29, 2016, we had approximately 34 holders of record of our common stock. The actual number of stockholders is greater than this number of record holders, and includes stockholders who are beneficial owners but whose shares are held in street name by brokers and other nominees.

Since becoming a public company, we have not declared or paid cash dividends on our common stock, nor do we intend to pay cash dividends on our common stock in the foreseeable future. However, in the future, subject to the factors described below and our future liquidity and capitalization, we may change this policy and choose to pay dividends.

We are a holding company that does not conduct any business operations of our own. As a result, our ability to pay cash dividends on our common stock is dependent upon cash dividends and distributions and other transfers from our subsidiaries. The ability of our subsidiaries to pay dividends is currently restricted by the terms of our credit agreement, and may be further restricted by any future indebtedness we or they incur. In addition, under Delaware law, our Board may declare dividends only to the extent of our surplus (which is defined as total assets at fair market value minus total liabilities, minus statutory capital) or, if there is no surplus, out of our net profits for the then current and/or immediately preceding fiscal year.

Any future determination to pay dividends will be at the discretion of our Board and will take into account restrictions in our debt instruments, including our credit agreement, general economic business conditions, our financial condition, results of operations and cash flows, our capital requirements, our business prospects, the ability of our operating subsidiaries to pay dividends and make distributions to us, legal restrictions, and such other factors as our Board may deem relevant.

See “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources” incorporated by reference from our Annual Report on Form 10-K for the fiscal year ended December 31, 2015 and our Quarterly Report on Form 10-Q for the quarter ended March 31, 2016.

In the years ended December 31, 2014 and 2013, we paid special dividends of $0.4 million and $0.5 million, respectively, to holders of our former Class C common stock. The Company redeemed the outstanding share of Class C common stock and eliminated the Class C common stock from its authorized capital stock in connection with the IPO in November 2014. Additionally, we utilized proceeds from our IPO of $3.4 million to terminate the advisory services agreement and $3.4 million to redeem Class C common stock.

The following table and accompanying footnotes sets forth information as of April 21, 2016 regarding the beneficial ownership of the selling stockholders in this offering. A person is a “beneficial owner” of a security if that person has or shares “voting power,” which includes the power to vote or to direct the voting of the security, or “investment power,” which includes the power to dispose of or to direct the disposition of the security or has the right to acquire such powers within 60 days. Percentage of beneficial ownership is based on 54,221,660 shares of common stock outstanding as of April 21, 2016 and 54,221,660 shares of common stock outstanding after giving effect to this offering.

The following discussion summarizes certain material U.S. federal income and estate tax consequences to non-U.S. holders (as defined below) of ownership and disposition of our common stock. This summary does not provide a complete analysis of all potential U.S. federal income tax and estate tax considerations relating thereto. The information provided below is based on the Internal Revenue Code of 1986, as amended (the “Code”), and administrative pronouncements, judicial decisions and final, temporary and proposed Treasury regulations as of the date hereof, changes to any of which subsequent to the date of this prospectus supplement may affect the tax consequences described herein. In addition, this summary does not address the Medicare tax on certain investment income or any state, local or foreign taxes or any U.S. federal tax laws other than, to the extent discussed below, U.S. federal income tax laws and estate tax laws. Furthermore, this discussion does not address the tax consequences to the selling stockholders of the ownership and disposition of our common stock. Persons considering the purchase, ownership, or disposition of our common stock should consult their tax advisors concerning U.S. federal, state, local, foreign or other tax consequences in light of their particular situations.

As used in this section, a “non-U.S. holder” is a beneficial owner of our common stock that is not, for U.S. federal income tax purposes:

If you are a non-U.S. citizen that is an individual, you may, in many cases, be deemed to be a resident alien, as opposed to a nonresident alien, by virtue of being present in the United States for at least 31 days in the calendar year and for an aggregate of at least 183 days during a three-year period ending in the current calendar year. For these purposes, all the days present in the current year, one-third of the days present in the immediately preceding year, and one-sixth of the days present in the second preceding year are counted. Resident aliens are subject to U.S. federal income tax as if they were U.S. citizens. Such an individual is urged to consult his or her own tax advisor regarding the U.S. federal income tax consequences of the ownership or disposition of our common stock. If an entity that is classified as a partnership for U.S. federal income tax purposes is a beneficial owner of our common stock, the tax treatment of a partner will generally depend on the status of the partner and upon the activities of the partnership. If you are a partner of a partnership holding shares of our common stock, you should consult your own tax advisor.

This discussion assumes that a non-U.S. holder will hold our common stock as a capital asset (generally, property held for investment). The summary generally does not address tax considerations that may be relevant to particular investors because of their specific circumstances, or because they are subject to special rules, including, without limitation, if the investor is a “controlled foreign corporation,” “passive foreign investment company,” former citizen or long-term resident of the United States or partnership or other pass-through entity for U.S. federal income tax purposes. If you fall within any of the foregoing categories, this description does not apply to you, and you should consult with your own tax advisor about the tax consequences of acquiring, owning, and disposing of our common stock.

INVESTORS CONSIDERING THE PURCHASE OF OUR COMMON STOCK SHOULD CONSULT THEIR OWN TAX ADVISORS REGARDING THE APPLICATION OF THE U.S. FEDERAL INCOME AND ESTATE TAX LAWS TO THEIR PARTICULAR SITUATIONS AND THE CONSEQUENCES OF FOREIGN, STATE OR LOCAL LAWS AND TAX TREATIES.

We do not expect to declare or pay any dividends on our common stock in the foreseeable future. If we do pay dividends on shares of our common stock, however, such distributions will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. Distributions in excess of our current and accumulated earnings and profits will constitute a return of capital that is applied against and reduces, but not below zero, a non-U.S. holder’s adjusted tax basis in shares of our common stock. Any remaining excess will be treated as gain realized on the sale or other disposition of our common stock. See “—Dispositions of Common Stock.”

Any dividend paid to a non-U.S. holder on our common stock will generally be subject to U.S. federal withholding tax at a 30% rate. The withholding tax might not apply, however, or might apply at a reduced rate, under the terms of an applicable income tax treaty between the United States and the non-U.S. holder’s country of residence. You should consult your tax advisors regarding your entitlement to benefits under a relevant income tax treaty. Generally, in order for us or our paying agent to withhold tax at a lower treaty rate, a non-U.S. holder must certify its entitlement to treaty benefits. A non-U.S. holder generally can meet this certification requirement by providing a properly completed Internal Revenue Service (“IRS”) Form W-8BEN or W-8BEN-E, as applicable (or any successor form), or appropriate substitute form to us or our paying agent. If the non-U.S. holder holds the common stock through a financial institution or other agent acting on the holder’s behalf, the holder will be required to provide appropriate documentation to the agent. The holder’s agent will then be required to provide certification to us or our paying agent, either directly or through other intermediaries.

Dividends received by a non-U.S. holder that are effectively connected with a U.S. trade or business conducted by the non-U.S. holder, and if required by an applicable income tax treaty between the United States and the non-U.S. holder’s country of residence, are attributable to a permanent establishment (or, in certain cases involving individual holders, a fixed base) maintained by the non-U.S. holder in the United States, are not subject to such withholding tax. To obtain this exemption, a non-U.S. holder must provide us with an IRS Form W-8ECI (or an acceptable substitute) properly certifying such exemption. Such effectively connected dividends, although not subject to withholding tax, are taxed at the same graduated rates applicable to U.S. persons, net of certain deductions and credits. In addition to the graduated tax described above, such effectively connected dividends received by corporate non-U.S. holders may also be subject to a branch profits tax at a rate of 30% or such lower rate as may be specified by an applicable tax treaty.

Subject to the discussion below on backup withholding and other withholding requirements, gain realized by a non-U.S. holder on a sale, exchange or other disposition of our common stock generally will not be subject to U.S. federal income or withholding tax, unless:

Generally, a corporation is a USRPHC if the fair market value of its “United States real property interests” equals 50% or more of the sum of the fair market value of (a) its worldwide real property interests and (b) its other assets used or held for use in a trade or business. The tax relating to stock in a USRPHC does not apply to a non-U.S. holder whose holdings, actual and constructive, amount to 5% or less of our common stock at all times during the applicable period, provided that our common stock is regularly traded on an established securities market. We believe we have not been and are not currently a USRPHC, and do not anticipate being a USRPHC in the future.

If any gain from the sale, exchange or other disposition of our common stock, (1) is effectively connected with a U.S. trade or business conducted by a non-U.S. holder and (2) if required by an applicable income tax treaty between the United States and the non-U.S. holder’s country of residence, is attributable to a permanent establishment (or, in certain cases involving individuals, a fixed base) maintained by such non-U.S. holder in the United States, then the gain generally will be subject to U.S. federal income tax at the same graduated rates applicable to U.S. persons, net of certain deductions and credits. If the non-U.S. holder is a corporation, it also may be subject to the branch profits tax at a 30% rate, or such lower rate as may be specified by an applicable income tax treaty.

The estates of nonresident alien individuals generally are subject to U.S. federal estate tax on property with a U.S. situs. Because we are a U.S. corporation, our common stock will be U.S. situs property and therefore will be included in the taxable estate of a nonresident alien decedent, unless an applicable estate tax treaty between the United States and the decedent’s country of residence provides otherwise.

Any dividends on our common stock that are paid to a non-U.S. holder must be reported annually to the IRS and to the non-U.S. holder. Copies of these information returns also may be made available to the tax authorities of the country in which the non-U.S. holder resides under the provisions of various treaties or agreements for the exchange of information. Unless the non-U.S. holder is an exempt recipient, dividends paid on our common stock and the gross proceeds from a taxable disposition of our common stock may be subject to additional information reporting and may also be subject to U.S. federal backup withholding (at a rate of 28%) if such non-U.S. holder fails to comply with applicable U.S. information reporting and certification requirements. Provision of any properly completed IRS Form W-8 appropriate to the non-U.S. holder’s circumstances will satisfy the certification requirements necessary to avoid the backup withholding tax.

Backup withholding is not an additional tax. Any amounts so withheld under the backup withholding rules will be refunded by the IRS or credited against the non-U.S. holder’s U.S. federal

income tax liability, provided that the required information is timely furnished to the IRS. Notwithstanding the foregoing, backup withholding and information reporting may apply if either we or our paying agent has actual knowledge, or reason to know, that a holder is a U.S. person and not a non-U.S. holder.

In addition to the withholding taxes discussed above, if a non-U.S. holder is a certain type of foreign entity (including, in some instances, a foreign entity acting as an intermediary), withholding tax of 30% under sections 1471 through 1474 of the Code (enacted by the Foreign Account Tax Compliance Act and commonly referred to as “FATCA”) will be imposed on dividends on our common stock and, after December 31, 2018, on the gross proceeds of dispositions of our common stock, unless such holder has satisfied various U.S. information reporting and due diligence requirements generally relating to its U.S. owners and account holders or otherwise qualifies for an exemption from these rules. These new requirements are different from, and in addition to, the beneficial owner certification requirements described above. If a non-U.S. holder is located in a jurisdiction that has an intergovernmental agreement with the United States governing FATCA, such holder may be subject to different rules. Non-U.S. holders should consult their tax advisors regarding the possible implications of FATCA on their investment in our common stock.

THE PRECEDING DISCUSSION OF U.S. FEDERAL TAX CONSIDERATIONS IS FOR GENERAL INFORMATION ONLY. IT IS NOT TAX ADVICE. EACH PROSPECTIVE INVESTOR SHOULD CONSULT ITS OWN TAX ADVISOR REGARDING THE PARTICULAR U.S. FEDERAL, STATE, LOCAL AND FOREIGN TAX CONSEQUENCES OF PURCHASING, HOLDING AND DISPOSING OF OUR COMMON STOCK, INCLUDING THE CONSEQUENCES OF ANY PROPOSED CHANGE IN APPLICABLE LAWS.

J.P. Morgan Securities LLC is acting as underwriter of the offering. Subject to the terms and conditions set forth in an underwriting agreement between us, the selling stockholders and the underwriter, the selling stockholders have agreed to sell to the underwriter, and the underwriter has agreed to purchase from the selling stockholders 8,000,000 shares of our common stock.

Subject to the terms and conditions set forth in the underwriting agreement, the underwriter has agreed to purchase all of the shares sold under the underwriting agreement if any of these shares are purchased.

We and the selling stockholders have agreed to indemnify the underwriter against certain liabilities, including liabilities under the Securities Act, or to contribute to payments the underwriter may be required to make in respect of those liabilities.

The underwriter is offering the shares, subject to prior sale, when, as and if issued to and accepted by them, subject to approval of legal matters by their counsel, including the validity of the shares, and other conditions contained in the underwriting agreement, such as the receipt by the underwriter of officer’s certificates and legal opinions. The underwriter reserves the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.

The underwriter is purchasing the shares of common stock from the selling stockholders at $ per share (representing approximately $ aggregate proceeds to the selling stockholders, before expenses). The underwriter may offer the shares of common stock from time to time for sale in one or more transactions on the NASDAQ, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. In connection with the sale of the shares of common stock offered hereby, the underwriter may be deemed to have received compensation in the form of underwriting discounts. The underwriter may effect such transactions by selling shares of common stock to or through dealers, and such dealers may receive compensation in the form of discounts, concessions or commissions from the underwriter and / or purchasers of shares of Class A common stock for whom they may act as agents or to whom they may sell as principal.

The expenses of the offering, not including the underwriting discounts, are estimated at $550,000 and are payable by us. We have agreed to reimburse the underwriter for expenses relating to clearing of this offering with FINRA in an amount up to $30,000.

We, our executive officers and directors and the selling stockholders have agreed not to sell or transfer any common stock or securities convertible into, exchangeable for, exercisable for, or repayable with common stock, for 30 days after the date of this prospectus supplement, with certain limited exceptions, without first obtaining the written consent of the underwriter. This lock-up provision applies to common stock and to securities convertible into or exchangeable or exercisable for or repayable with common stock. It also applies to common stock owned now or acquired later by the person executing the agreement or for which the person executing the agreement later acquires the power of disposition.

In connection with the offering, the underwriter may purchase and sell our common stock in the open market. These transactions may include short sales and purchases on the open market to cover positions created by short sales. Short sales involve the sale by the underwriter of a greater number of shares than they are required to purchase in the offering. “Covered” short sales are sales made in an amount not greater than the underwriter’s option to purchase additional shares described above. The underwriter may close out any covered short position by either exercising their option to purchase additional shares or purchasing shares in the open market. In determining the source of shares to close out the covered short position, the underwriter will consider, among other things, the price of shares available for purchase in the open market as compared to the price at which they may purchase shares through the option granted to them. “Naked” short sales are sales in excess of such option. The underwriter must close out any naked short position by purchasing shares in the open market. A naked short position is more likely to be created if the underwriter is concerned that there may be downward pressure on the price of our common stock in the open market after pricing that could adversely affect investors who purchase in the offering.

Similar to other purchase transactions, the underwriter’s purchases to cover the syndicate short sales may have the effect of raising or maintaining the market price of our Class A common stock or preventing or retarding a decline in the market price of our Class A common stock. As a result, the price of our Class A common stock may be higher than the price that might otherwise exist in the open market. The underwriter may conduct these transactions on NASDAQ, in the over-the-counter market or otherwise.

None of us, the selling stockholders or the underwriter make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of our Class A common stock. In addition, neither we, the selling stockholders nor the underwriter make any representation that the underwriter will engage in these transactions or that these transactions, once commenced, will not be discontinued without notice.

In connection with this offering, the underwriter may engage in passive market making transactions in the Class A common stock on the NASDAQ in accordance with Rule 103 of Regulation M under the Exchange Act during a period before the commencement of offers or sales of Class A common stock and extending through the completion of distribution. A passive market maker must display its bid at a price not in excess of the highest independent bid of that security. However, if all independent bids are lowered below the passive market maker’s bid, that bid must then be lowered when specified purchase limits are exceeded. Passive market making may cause the price of our Class A common stock to be higher than the price that otherwise would exist in the open market in the absence of those transactions. The underwriter is not required to engage in passive market making and may end passive market making activities at any time.

In connection with the offering, the underwriter may distribute prospectuses by electronic means, such as e-mail.

The underwriter and its affiliates have engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with us or our affiliates. The underwriter has received, or may in the future receive, customary fees and commissions for these transactions.

In addition, in the ordinary course of its business activities, the underwriter and its affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers. Such investments and securities activities may involve securities and/or instruments of ours or our affiliates. The underwriter and its affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

In relation to each member state of the European Economic Area, no offer of ordinary shares which are the subject of the offering has been, or will be made to the public in that Member State, other than under the following exemptions under the Prospectus Directive:

provided that no such offer of ordinary shares referred to in (a) to (c) above shall result in a requirement for the Company or any Representative to publish a prospectus pursuant to Article 3 of the Prospectus Directive, or supplement a prospectus pursuant to Article 16 of the Prospectus Directive.

Each person located in a Member State to whom any offer of ordinary shares is made or who receives any communication in respect of an offer of ordinary shares, or who initially acquires any ordinary shares will be deemed to have represented, warranted, acknowledged and agreed to and with each Representative and the Company that (1) it is a “qualified investor” within the meaning of the law in that Member State implementing Article 2(1)(e) of the Prospectus Directive; and (2) in the case of any ordinary shares acquired by it as a financial intermediary as that term is used in Article 3(2) of the Prospectus Directive, the ordinary shares acquired by it in the offer have not been acquired on behalf of, nor have they been acquired with a view to their offer or resale to, persons in any Member State other than qualified investors, as that term is defined in the Prospectus Directive, or in circumstances in which the prior consent of the Representatives has been given to the offer or resale; or where ordinary shares have been acquired by it on behalf of persons in any Member State other than qualified investors, the offer of those ordinary shares to it is not treated under the Prospectus Directive as having been made to such persons.

The Company, our representatives and their respective affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgments and agreements.

This prospectus supplement has been prepared on the basis that any offer of shares in any Member State will be made pursuant to an exemption under the Prospectus Directive from the

requirement to publish a prospectus for offers of shares. Accordingly any person making or intending to make an offer in that Member State of shares which are the subject of the offering contemplated in this prospectus may only do so in circumstances in which no obligation arises for the Company or any of the Representatives to publish a prospectus pursuant to Article 3 of the Prospectus Directive in relation to such offer. Neither the Company nor the Representatives have authorized, nor do they authorize, the making of any offer of shares in circumstances in which an obligation arises for the Company or the Representatives to publish a prospectus for such offer.

For the purposes of this provision, the expression an “offer of ordinary shares to the public” in relation to any ordinary shares in any Member State means the communication in any form and by any means of sufficient information on the terms of the offer and the ordinary shares to be offered so as to enable an investor to decide to purchase or subscribe the ordinary shares, as the same may be varied in that Member State by any measure implementing the Prospectus Directive in that Member State, the expression “Prospectus Directive” means Directive 2003/71/EC (as amended) and includes any relevant implementing measure in each Member State.

In addition, in the United Kingdom, this document is being distributed only to, and is directed only at, and any offer subsequently made may only be directed at persons who are “qualified investors” (as defined in the Prospectus Directive) (i) who have professional experience in matters relating to investments falling within Article 19 (5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the “Order”) and/or (ii) who are high net worth companies (or persons to whom it may otherwise be lawfully communicated) falling within Article 49(2)(a) to (d) of the Order (all such persons together being referred to as “relevant persons”). This document must not be acted on or relied on in the United Kingdom by persons who are not relevant persons. In the United Kingdom, any investment or investment activity to which this document relates is only available to, and will be engaged in with, relevant persons.

The shares may not be publicly offered in Switzerland and will not be listed on the SIX Swiss Exchange (“SIX”) or on any other stock exchange or regulated trading facility in Switzerland. This document has been prepared without regard to the disclosure standards for issuance prospectuses under art. 652a or art. 1156 of the Swiss Code of Obligations or the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading facility in Switzerland. Neither this document nor any other offering or marketing material relating to the shares or the offering may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this document nor any other offering or marketing material relating to the offering, the Company, the shares have been or will be filed with or approved by any Swiss regulatory authority. In particular, this document will not be filed with, and the offer of shares will not be supervised by, the Swiss Financial Market Supervisory Authority FINMA (FINMA), and the offer of shares has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes (“CISA”). The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to acquirers of shares.

This prospectus supplement relates to an Exempt Offer in accordance with the Offered Securities Rules of the Dubai Financial Services Authority (“DFSA”). This prospectus supplement is intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement nor taken steps to verify the information set forth herein and has no responsibility for the prospectus supplement. The shares to which this prospectus supplement relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the shares offered should conduct their own due diligence on the shares. If you do not understand the contents of this prospectus supplement you should consult an authorized financial advisor.

No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission (“ASIC”), in relation to the offering. This prospectus supplement does not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001 (the “Corporations Act”), and does not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.

Any offer in Australia of the shares may only be made to persons (the “Exempt Investors”) who are “sophisticated investors” (within the meaning of section 708(8) of the Corporations Act), “professional investors” (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act so that it is lawful to offer the shares without disclosure to investors under Chapter 6D of the Corporations Act.

The shares applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under the offering, except in circumstances where disclosure to investors under Chapter 6D of the Corporations Act would not be required pursuant to an exemption under section 708 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapter 6D of the Corporations Act. Any person acquiring shares must observe such Australian on-sale restrictions.

This prospectus supplement contains general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus supplement is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

The shares of common stock have not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than (a) to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong and any rules made under that Ordinance; or (b) in other circumstances which do not result in the document being a “prospectus” as defined in the Companies Ordinance (Cap. 32) of Hong Kong or which do not constitute an offer to the public within the meaning of that Ordinance. No advertisement, invitation or document relating to the shares of common stock have been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of

which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to shares of common stock which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the Securities and Futures Ordinance and any rules made under that Ordinance.

The shares have not been and will not be registered under the Financial Instruments and Exchange Law of Japan (Law No. 25 of 1948, as amended) and, accordingly, will not be offered or sold, directly or indirectly, in Japan, or for the benefit of any Japanese Person or to others for re-offering or resale, directly or indirectly, in Japan or to any Japanese Person, except in compliance with all applicable laws, regulations and ministerial guidelines promulgated by relevant Japanese governmental or regulatory authorities in effect at the relevant time. For the purposes of this paragraph, “Japanese Person” shall mean any person resident in Japan, including any corporation or other entity organized under the laws of Japan.

This prospectus supplement has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of shares may not be circulated or distributed, nor may the shares be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the “SFA”), (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to Section 275(1A), and in accordance with the conditions specified in Section 275, of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

Where the shares are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

securities (as defined in Section 239(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the shares pursuant to an offer made under Section 275 of the SFA except:

The shares of common stock may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations . Any resale of the shares of common stock must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 (or, in the case of securities issued or guaranteed by the government of a non-Canadian jurisdiction, section 3A.4) of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriter is not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

Wyrick Robbins Yates & Ponton LLP, Raleigh, North Carolina, has passed upon the validity of the shares of common stock offered under this prospectus supplement. Certain legal matters in connection with the offering will be passed upon for the underwriters by Latham & Watkins LLP, New York, New York.

The consolidated financial statements of INC Research Holdings, Inc. appearing in INC Research Holdings, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2015 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

We have filed with the SEC a registration statement on Form S-3 under the Securities Act with respect to the shares of common stock offered hereby. This prospectus supplement, which constitutes part of the registration statement, does not contain all of the information set forth in the registration statement and the exhibits and schedules thereto. For further information with respect to us and the shares of common stock offered hereby, you should refer to the registration statement and to the exhibits and schedules filed therewith. Statements contained in this prospectus supplement regarding the contents of any contract or any other document that is filed as an exhibit to the registration statement are not necessarily complete, and each such statement is qualified in all respects by reference to the full text of such contract or other document filed as an exhibit to the registration statement. We are also required to file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings, including our registration statement and the exhibits and schedules thereto, may be inspected without charge at the public reference room maintained by the SEC located at 100 F Street, N.E., Room 1580, Washington, D.C. 20549. Copies of all or any portion of the registration statements and the filings may be obtained from such offices upon payment of prescribed fees. The public may obtain information on the operation of the public reference room by calling the SEC at (800) SEC-0330 or (202) 551-8090. The SEC maintains a website at www.sec.gov that contains reports, proxy and information statements and other information regarding registrants that file electronically with the SEC.

You may obtain a copy of any of our filings, at no cost, by writing or telephoning us at:

The SEC allows us to “incorporate by reference” information we file with it into our registration statement of which this prospectus supplement is a part, which means that we can disclose important information to you by referring you to other documents. The information incorporated by reference is

considered to be part of this prospectus supplement. We incorporate by reference into this prospectus supplement the documents listed below, except for information “furnished” under Items 2.02 or 7.01 on Form 8-K or other information “furnished” to the SEC which is not deemed filed and not incorporated in this prospectus supplement.

We will provide to each person, including any beneficial owners, to whom a prospectus is delivered, upon written or oral request of any such person, a copy of the reports and documents that have been incorporated by reference into this prospectus supplement, at no cost. Any such request should be directed to: INC Research Holdings, Inc., 3201 Beechleaf Court, Raleigh, North Carolina 27604, Attention: Corporate Secretary (919) 876-9300. These documents are also available on the Investor Relations section of our website, which is located at http://www.incresearch.com, or as described under “Where You Can Find Additional Information” above. The reference to our website address does not constitute incorporation by reference of the information contained on our website.

Any statement in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for the purposes of this registration statement to the extent that a statement contained herein modifies or supersedes such statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this registration statement.

You should rely only on the information incorporated by reference or provided in this prospectus supplement or the accompanying prospectus. We have not authorized anyone else to provide you with different information.

We may offer and sell shares of our Class A common stock, or common stock, from time to time in amounts, at prices and on terms that will be determined at the time of the offering.The selling stockholders to be named in a prospectus supplement may also offer and sell shares of our common stock from time to time in one or more offerings in amounts, at prices and on terms that will be determined at the time of such offerings. We will not receive any of the proceeds from the sale of our common stock by selling stockholders.

This prospectus describes the general manner in which these shares of our common stock may be offered and sold. More specific information, including the manner in which shares of common stock may be offered and sold and the prices and the net proceeds from the sales of such common stock will be described in a prospectus supplement to this prospectus. In the case of an offering by selling stockholders, information about the selling stockholders, including the relationship between the selling stockholders and us, will also be included in the applicable prospectus supplement. The prospectus supplement or free writing prospectus may also add, update or change information contained in this prospectus.

You should carefully read this prospectus and any accompanying prospectus supplement, together with documents we incorporate by reference, before you invest in our common stock. This prospectus may not be used to sell shares of our common stock unless accompanied by a prospectus supplement.

Investing in our common stock involves risks. See “Risk Factors” beginning on page 3, in any accompanying prospectus supplement and in the documents incorporated by reference into this prospectus to read about factors you should consider before investing in our common stock.

Our Class A common stock is listed on the NASDAQ Global Select Market, or NASDAQ, under the symbol “INCR.”

Neither the Securities and Exchange Commission nor any other regulatory body has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

This prospectus is part of a registration statement on Form S-3 that we filed with the United States Securities and Exchange Commission, or the SEC, as a “well-known seasoned issuer” as defined under Rule 405 under the Securities Act of 1933, as amended, or the Securities Act, using a “shelf” registration process. By using a shelf registration statement, we and/or the selling stockholders to be named in a prospectus supplement to this prospectus may, as applicable, from time to time, sell shares of our common stock in one or more offerings. Each time that we and/or the selling stockholders sell securities under this shelf registration statement, we will provide a prospectus supplement that will contain specific information about the terms of that offering. A prospectus supplement may also add, update or change information contained in this prospectus with respect to that offering, including information about the selling stockholders. If there is any inconsistency between the information in this prospectus and an applicable prospectus supplement, you should rely on the prospectus supplement. Before purchasing any securities, you should carefully read both this prospectus and any applicable prospectus supplement or free writing prospectus we file with the SEC, together with the additional information described under the headings “Where You Can Find More Information” and “Incorporation of Documents by Reference.”

The rules of the SEC allow us to incorporate by reference information into this prospectus. This means that important information is contained in other documents that are considered to be a part of this prospectus. Additionally, information that we file later with the SEC will automatically update and supersede this information. You should carefully read both this prospectus and the applicable prospectus supplement together with the additional information that is incorporated or deemed incorporated by reference in this prospectus. See “Incorporation of Documents by Reference” before making an investment in our common stock. This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of the documents referred to herein have been filed or will be filed or incorporated by reference as exhibits to the registration statement of which this prospectus is a part. The registration statement, including the exhibits and documents incorporated or deemed incorporated by reference in this prospectus, can be read on the SEC website or at the SEC offices mentioned under the heading “Where You Can Find More Information.”

THIS PROSPECTUS MAY NOT BE USED TO SELL ANY SHARES OF OUR COMMON STOCK UNLESS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

Neither the delivery of this prospectus or any applicable prospectus supplement nor any sale made using this prospectus or any applicable prospectus supplement implies that there has been no change in our affairs or that the information in this prospectus or in any applicable prospectus supplement is correct as of any date after their respective dates. You should not assume that the information included in or incorporated by reference in this prospectus or any applicable prospectus supplement or any free writing prospectus prepared by us, is accurate as of any date other than the date(s) on the front covers of those documents. Our business, financial condition, results of operations and prospects may have changed since those dates.

You should rely only on the information contained in or incorporated by reference in this prospectus or a prospectus supplement. We have not authorized anyone to give you different information, and if you are given any information that is not contained or incorporated by reference in this prospectus or a prospectus supplement, you must not rely on that information. We and any selling stockholders are not making an offer to sell securities in any jurisdiction where the offer or sale of such securities is not permitted.

We have filed or incorporated by reference exhibits to the registration statement of which this prospectus is a part. You should read the exhibits carefully for provisions that may be important to you.

Unless the context requires otherwise, references to “our company,” “we,” “us” and “our” refer to INC Research Holdings, Inc. and its direct and indirect subsidiaries; references to “INC Holdings” refer to INC Research Holdings, Inc.; and references to “INC” refer to INC Research, LLC, our wholly-owned subsidiary. Unless the context otherwise requires, references to “common stock” refer to our Class A common stock. References to GAAP are to the generally accepted accounting principles of the United States. References to the “Sponsors” refer to affiliates of Avista Capital Partners II, L.P., and affiliates of Teachers Private Capital, the private investment arm of Ontario Teachers Pension Plan Board.

Investing in our common stock involves a high degree of risk. You should consider carefully the risks and uncertainties described in “Risk Factors” and elsewhere in our most recently filed Annual Report on Form 10-K filed with the SEC, in each case as these risk factors are amended or supplemented by subsequent Quarterly Reports on Form 10-Q that have been or will be incorporated by reference in this prospectus. The prospectus supplement relating to a particular offering of common stock may also discuss certain risks of investing in that offering. The occurrence of any of such risks may materially and adversely affect our business, financial condition, results of operations and future prospects. In such an event, the market price of our common stock could decline, and you could lose part or all of your investment.

This prospectus (including any prospectus supplement and the information incorporated or deemed to be incorporated by reference in this prospectus) and any free writing prospectus that we may provide to you in connection with an offering of our common stock described in this prospectus contains forward-looking statements within the meaning of Section 27A of the Securities Act. All statements other than statements of historical facts contained in this prospectus, including statements regarding our future results of operations and financial position, business strategy and plans and our objectives for future operations, are forward-looking statements. The words “anticipates,” “believes,” “can,” “continue,” “could,” “estimates,” “expects,” “intends,” “seeks,” “may,” “might,” “plans,” “projects,” “should,” “would,” “targets,” “will” and the negative thereof and similar words and expressions are intended to identify forward-looking statements. Examples of forward-looking statements include, but are not limited to, statements we make regarding: (i) trends in R&D spending, outsourcing penetration rates and the incremental growth of the late-stage clinical development services market relative to the overall market; (ii) fast growing therapeutic areas; and (iii) the continuous enhancement of our Trusted Process ^® to deliver superior outcomes. Forward-looking statements are based largely on our current expectations and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy, short-term and long-term business operations and objectives, and financial needs. These forward-looking statements are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict. Moreover, we operate in a very competitive and rapidly changing environment. New risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties and assumptions, the forward-looking events and circumstances discussed in this prospectus might not occur and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements. We caution you therefore against relying on these forward-looking statements.

The forward-looking statements included in this prospectus, any prospectus supplement and the documents incorporated by referenced into this prospectus are made only as of the date hereof and thereof. You should not rely upon forward-looking statements as predictions of future events. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances reflected in the forward-looking statements will be achieved or occur. Moreover, neither we nor any other person assumes responsibility for the accuracy and completeness of the forward-looking statements. We undertake no obligation to update publicly any forward-looking statements for any reason after the date of this prospectus or the documents incorporated by reference into this prospectus to conform these statements to actual results or to changes in our expectations, except as may be required by law.

You should read this prospectus, any prospectus supplement or the documents incorporated by reference into this prospectus with the understanding that our actual future results, levels of activity, performance and events and circumstances may be materially different from what we expect.

We are a leading global Contract Research Organization based on revenues. We focus on Phase I to Phase IV clinical development services for the biopharmaceutical and medical device industries. We provide our customers highly differentiated therapeutic alignment and expertise, with a particular strength in central nervous system, oncology and other complex diseases. We consistently and predictably deliver clinical development services in a complex environment and offer a proprietary, operational approach to clinical trials through our Trusted Process ^® methodology. Our service offerings focus on optimizing the development of, and therefore, the commercial potential for, our customers’ new biopharmaceutical compounds, enhancing returns on their research and development investments and reducing their overhead by offering an attractive variable cost alternative to fixed cost, in-house resources.

We are a Delaware corporation and were incorporated on August 13, 2010. Our principal executive office is located at 3201 Beechleaf Court, Suite 600, Raleigh, North Carolina 27604-1547. Our telephone number at our principal executive office is (919) 876-9300. Our common stock is currently traded on the NASDAQ under the stock symbol “INCR”. Our corporate website is www.incresearch.com. The information contained on our website or that can be accessed through our website neither constitutes part of this prospectus nor is incorporated by reference herein.

In the case of a sale of shares of our common stock by us, the use of proceeds will be specified in the applicable prospectus supplement. In the case of a sale of shares of our common stock by any selling stockholder, we will not receive any proceeds from the sale of our common stock.

Selling stockholders are persons or entities that, directly or indirectly, have acquired or will from time to time acquire from us, common stock in various private transactions. Such selling stockholders may be parties to registration rights agreements with us, or we otherwise may have agreed or will agree to register their shares of common stock for resale. The initial purchasers of our common stock, as well as their transferees, pledgees, donees or successors, all of whom we refer to as “selling stockholders,” may from time to time offer and sell the securities pursuant to this prospectus and any applicable prospectus supplement.

In addition to covering the offering of common stock by us, this prospectus covers the offering for resale of common stock by selling stockholders. Information about selling stockholders, if any, will be set forth in a prospectus supplement, in an amendment to the registration statement of which this prospectus is a part, or in other filings we make with the SEC under the Securities Exchange Act of 1934, as amended, or the Exchange Act, which are incorporated by reference into this prospectus.

The following discussion is a summary of the terms of our common stock, our amended and restated certificate of incorporation, our amended and restated bylaws and certain applicable provisions of Delaware law, as currently in effect. This summary does not purport to be complete and is qualified in its entirety by reference to the actual terms and provision of our amended and restated certificate of incorporation and amended and restated bylaws, copies of which have been filed previously with the SEC. For more information on how you can obtain copies of our amended and restated certificate of incorporation and amended and restated bylaws, see “Where You Can Find More Information.”

Our authorized capital stock consists of (i) 300 million shares of Class A common stock, par value $0.01 per share, (ii) 300 million shares of Class B common stock, par value $0.01 per share, and (iii) 30 million shares of preferred stock, par value $0.01 per share.

As of December 1, 2015, 56,504,163 shares of our Class A common stock were outstanding and no shares of Class B common stock outstanding. Holders of our common stock are entitled to the following rights.

Each share of our Class A common stock entitles its holder to one vote per share on all matters to be voted upon by the stockholders. Each share of our Class B common stock entitles its holder to one vote per share on all matters to be voted upon by stockholders, except with respect to the election or removal of directors. Holders of Class A common stock and Class B common stock vote together as a single class. There is no cumulative voting, which means that a holder or group of holders of more than 50% of the shares of our common stock can elect all of our directors.

The holders of our common stock are entitled to receive dividends when and as declared by our Board of Directors, which we refer to as our Board, from legally available sources, subject to the prior rights of the holders of our preferred stock, if any.

The shares of Class B common stock are convertible into Class A common stock, in whole or in part, at any time and from time to time at the option of the holder, on the basis of one share of Class A common stock for each share of Class B common stock, subject to adjustment for any stock splits, combinations or similar events.

In the event of our liquidation or dissolution, the holders of our common stock will be entitled to share ratably in the assets available for distribution after the payment of all of our debts and other liabilities, subject to the prior rights of the holders of our preferred stock, if any.

Our common stockholders do not have preemptive or other rights to subscribe for additional shares. All holders of our common stock are entitled to share equally on a share-for-share basis in any assets available for distribution to common stockholders upon our liquidation, dissolution or winding up. All outstanding shares are, and all shares offered by this prospectus will be, when sold, validly issued, fully paid and nonassessable.

As of December 1, 2015, we had no shares of preferred stock outstanding. Our Board is authorized, without further stockholder approval, to issue from time to time up to an aggregate of 30 million shares of preferred stock in one or more series and to fix or alter the designations, preferences, rights and any qualifications, limitations or restrictions of the shares of each such series thereof, including the dividend rights, dividend rates, conversion rights, voting rights, terms of redemption (including sinking fund provisions), redemption price or prices, liquidation preferences and the number of shares constituting any series or designations of such series. As of the date of this prospectus, we had no plans to issue any shares of preferred stock.

Certain of our existing stockholders have certain registration rights with respect to our common stock pursuant to a stockholders agreement.

Our amended and restated certificate of incorporation and amended and restated bylaws contain provisions that could delay, defer or discourage transactions involving an actual or potential change in control of us or change in our management. We expect that these provisions, which are summarized below, might discourage coercive takeover practices or inadequate takeover bids. These provisions are also designed to encourage persons seeking to acquire control of us to first negotiate with our Board, which we believe may result in an improvement of the terms of any such acquisition in favor of our stockholders. However, they also give our Board the power to discourage transactions that some stockholders may favor, including transactions in which stockholders might otherwise receive a premium for their shares, or transactions that our stockholders might otherwise deem to be in their best interests. Accordingly, these provisions could adversely affect the price of our common stock.

Our amended and restated certificate of incorporation provides that our Board consists of eight directors, and that our Board will be divided into three classes, with one class being elected at each annual meeting of stockholders. Each director will serve a three-year term, with termination staggered according to class. Class I consists of two directors, Class II consists of three directors, and Class III consists of three directors. The size of our Board may thereafter be fixed from time to time solely by resolution of at least a majority of the directors then in office.

Our amended and restated certificate of incorporation provides that directors may only be removed for cause by the affirmative vote of the remaining members of the Board or the holders of at least a majority of the voting power of all outstanding shares of common stock then entitled to vote on the election of directors. Furthermore, any vacancy on our Board, however occurring, including a vacancy resulting from an increase in the size of our Board, may only be filled by the affirmative vote of a majority of our directors then in office, even if less than a quorum. Directors nominated by a Sponsor may be removed from office with or without cause by the affirmative vote of such Sponsor without a meeting.

The classification of our Board could make it more difficult for a third party to acquire, or discourage a third party from seeking to acquire, control of our company.

Requirements for Advance Notification of Stockholder Meetings, Nominations and Proposals

Our amended and restated bylaws provide that special meetings of the stockholders may be called only upon the request of a majority of our Board or upon the request of the Chief Executive Officer or the chair of the Board. Our amended and restated bylaws prohibit the conduct of any business at a special meeting other than as specified in the notice for such meeting. These provisions may have the effect of deferring, delaying or discouraging hostile takeovers or changes in control or management of our company.

Our amended and restated bylaws establish advance notice procedures with respect to stockholder proposals and the nomination of candidates for election as directors, other than nominations made by or at the direction of our Board or a committee of the Board. In order for any matter to be “properly brought” before a meeting, a stockholder has to comply with the advance notice requirements. Our amended and restated bylaws allow the presiding officer at a meeting of the stockholders to adopt rules and regulations for the conduct of meetings which may have the effect of precluding the conduct of certain business at a meeting if the rules and regulations are not followed. These provisions may also defer, delay or discourage a potential acquirer from conducting a solicitation of proxies to elect the acquirer’s own slate of directors or otherwise attempting to obtain control of our company.

Our amended and restated certificate of incorporation provides that, subject to the rights of any holders of preferred stock to act by written consent instead of a meeting, stockholder action may be taken only at an annual meeting or special meeting of stockholders and may not be taken by written consent instead of a meeting, unless the Sponsors and their affiliates own at least 50% of our outstanding common stock or the action to be taken by written consent of stockholders and the taking of this action by written consent has been expressly approved in advance by the Board. Failure to satisfy any of the requirements for a stockholder meeting could delay, prevent or invalidate stockholder action.

Our amended and restated certificate of incorporation provides that the provisions of Section 203 of the Delaware General Corporation Law, or DGCL, which relate to business combinations with interested stockholders, do not apply to us until the moment in time immediately following the time at which both the following conditions exist: (i) Section 203 of the DGCL by its terms, but for the terms of our amended and restated certificate of incorporation, apply to us; and (ii) there occurs a transaction following the consummation of which the Sponsors and their Sponsor affiliates no longer own at least 10% or more of our issued and outstanding common stock entitled to vote. Section 203 of the DGCL prohibits a publicly held Delaware corporation from engaging in a business combination transaction with an interested stockholder (a stockholder who owns more than 15% of our common stock) for a period of three years after the interested stockholder became such unless the transaction fits within an applicable exemption, such as board approval of the business combination or the transaction that resulted in such stockholder becoming an interested stockholder. These provisions would apply even if the business combination could be considered beneficial by some stockholders.

Our amended and restated certificate of incorporation provides that neither a Sponsor nor a director nominated by a Sponsor will have any obligation to offer us an opportunity to participate in business opportunities presented to such Sponsor even if the opportunity is one that we might reasonably have pursued and that, to the extent permitted by law, no Sponsor will be liable to us or our stockholders for breach of any duty by reason of any such activities. Therefore the Sponsors are free to compete with us in the same business or similar businesses.

Any amendment to our amended and restated certificate of incorporation must first be approved by a majority of our Board and (i) thereafter be approved by a majority of the outstanding shares entitled to vote on the amendment, or (ii) if related to provisions regarding the classification of the Board, the removal of directors, director vacancies, forum selection for certain lawsuits or the amendment of certain provisions of our bylaws or certificate of incorporation, thereafter be approved by at least 66 2 /3% of the outstanding shares entitled to vote on the amendment. A vote of the majority of Class B common stock, voting separately, is require to change the voting rights of Class B common stock or to change their rights disproportionately to those of Class A common stock. For so long as the Sponsors beneficially own 10% or more of our issued and outstanding common stock entitled to vote generally in the election of directors, any amendment to provisions regarding Section 203 of the DGCL or corporate opportunities must also receive the Sponsors’ prior written consent. Our bylaws may be amended (x) by the affirmative vote of a majority of the directors then in office, subject to any limitations set forth in the bylaws, without further stockholder action or (y) by the affirmative vote of at least 50.1% of the outstanding shares entitled to vote on the amendment, without further action by our Board.

The authorized but unissued shares of our common stock and our preferred stock will be available for future issuance without any further vote or action by our stockholders. These additional shares may be utilized for a variety of corporate purposes, including future public offerings to raise additional capital, corporate acquisitions and employee benefit plans. The existence of authorized but unissued shares of our common stock and our preferred stock could render more difficult or discourage an attempt to obtain control over us by means of a proxy contest, tender offer, merger or otherwise.

Our amended and restated certificate of incorporation provides that, subject to certain exceptions, the Court of Chancery of the State of Delaware shall be the sole and exclusive forum for certain stockholder litigation matters. However, it is possible that a court could rule that this provision is unenforceable or inapplicable.

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A.

We and/or the selling stockholders, if applicable, may sell shares of common stock from time to time pursuant to underwritten public offerings, negotiated transactions, block trades or a combination of these methods or through underwriters or dealers, through agents and/or directly to one or more purchasers. The securities may be distributed from time to time in one or more transactions:

Each time that we or any of the selling stockholders sell securities covered by this prospectus, we will provide a prospectus supplement or supplements that will describe the method of distribution and set forth the terms and conditions of the offering of such securities, including: (1) the name or names of any underwriters, dealers or agents and the amounts of securities underwritten or purchased by each of them; (2) the public offering price of the securities and the proceeds to us and/or the selling stockholders; (3) any options under which underwriters may purchase additional securities; (4) any underwriting discounts or commissions or agency fees and other items constituting underwriters’ or agents’ compensation; (5) terms and conditions of the offering and (6) any discounts, commissions or concessions allowed or reallowed or paid to dealers.

Offers to purchase the common stock being offered by this prospectus may be solicited directly. Agents may also be designated to solicit offers to purchase the common stock from time to time. Any agent involved in the offer or sale of our common stock, and any commissions paid to them, will be identified in a prospectus supplement. We may engage in “at the market” offerings into an existing trading market in accordance with Rule 415(a)(4) under the Securities Act.

If a dealer is utilized in the sale of the securities being offered by this prospectus, the securities will be sold 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 an underwriter is utilized in the sale of the securities being offered by this prospectus, an underwriting agreement will be executed with the underwriter at the time of sale and the name of any underwriter will be provided in the prospectus supplement that the underwriter will use to make resales of the securities to the public. In connection with the sale of the securities, we, the selling stockholders, or the purchasers of securities for whom the underwriter may act as agent, may compensate the underwriter in the form of underwriting discounts or commissions. The underwriter may sell the securities to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions from the purchasers for which they act as agent. Unless otherwise indicated in a prospectus supplement, an agent will be acting on a best efforts basis and a dealer will purchase securities as a principal, and may then resell the securities at varying prices to be determined by the dealer.

Any compensation paid to underwriters, dealers or agents in connection with the offering of the securities, and any discounts, concessions or commissions allowed by underwriters to participating dealers, will be disclosed in the applicable prospectus supplement. Underwriters, dealers and agents participating in the distribution of the securities may be deemed to be underwriters within the meaning of the Securities Act, and any discounts and commissions received by them and any profit realized by them on resale of the securities may be deemed to be underwriting discounts and commissions. We and the selling stockholders may each or both enter into agreements to indemnify underwriters,

dealers and agents against civil liabilities, including liabilities under the Securities Act, or to contribute to any payments they are required to make in respect thereof and to reimburse those persons for certain expenses.

Our common stock is listed on the NASDAQ. To facilitate the offering of securities, certain persons participating in the offering may engage in transactions that stabilize, maintain or otherwise affect the price of the securities. This may include over-allotments or short sales of the securities, which involve the sale by persons participating in the offering of more securities than were sold to them. In these circumstances, these persons would cover such over-allotments or short positions by making purchases in the open market or by exercising their over-allotment option, if any. In addition, these persons may stabilize or maintain the price of the securities by bidding for or purchasing securities in the open market or by imposing penalty bids, whereby selling concessions allowed to dealers participating in the offering may be reclaimed if securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. These transactions may be discontinued at any time.

If indicated in the applicable prospectus supplement, underwriters or other persons acting as agents may be authorized to solicit offers by institutions or other suitable purchasers to purchase the securities at the public offering price set forth in the prospectus supplement, pursuant to delayed delivery contracts providing for payment and delivery on the date or dates stated in the prospectus supplement. These purchasers may include, among others, commercial and savings banks, insurance companies, pension funds, investment companies and educational and charitable institutions. Delayed delivery contracts will be subject to the condition that the purchase of the securities covered by the delayed delivery contracts will not at the time of delivery be prohibited under the laws of any jurisdiction in the United States to which the purchaser is subject. The underwriters and agents will not have any responsibility with respect to the validity or performance of these contracts.

If at the time of any offering made under this prospectus a member of FINRA participating in the offering has a “conflict of interest” as defined in FINRA Rule 5121 (“Rule 5121”), that offering will be conducted in accordance with the relevant provisions of Rule 5121.

The specific terms of any lock-up provisions in respect of any given offering will be described in the applicable prospectus supplement.

The underwriters, dealers and agents may engage in other transactions with us, or perform other services for us, in the ordinary course of business for which they receive compensation.

Selling stockholders may also sell securities under Rule 144 under the Securities Act, if available, or pursuant to other available exemptions from the registration requirements under the Securities Act, rather than under this prospectus. Registration of the common stock covered by this prospectus does not mean that any shares of common stock will be offered or sold.

Wyrick Robbins Yates & Ponton LLP, Raleigh, North Carolina, has passed upon the validity of the shares of Class A common stock offered under this prospectus.

The consolidated financial statements of INC Research Holdings, Inc. appearing in INC Research Holdings, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2014 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

We have filed with the SEC a registration statement on Form S-3 under the Securities Act with respect to the shares of Class A common stock offered hereby. This prospectus, which constitutes part of the registration statement, does not contain all of the information set forth in the registration statement and the exhibits and schedules thereto. For further information with respect to us and the shares of Class A common stock offered hereby, you should refer to the registration statement (including this prospectus) and to the exhibits and schedules filed therewith. Statements contained in this prospectus regarding the contents of any contract or any other document that is filed as an exhibit to the registration statement are not necessarily complete, and each such statement is qualified in all respects by reference to the full text of such contract or other document filed as an exhibit to the registration statement.

We are also required to file annual, quarterly and current reports, proxy statements and other information with the SEC, some of which are incorporated by reference into this prospectus. Our SEC filings, including our registration statement and the exhibits and schedules thereto, may be inspected without charge at the public reference room maintained by the SEC located at 100 F Street, N.E., Room 1580, Washington, D.C. 20549. Copies of all or any portion of the registration statements and the filings may be obtained from such offices upon payment of prescribed fees. The public may obtain information on the operation of the public reference room by calling the SEC at (800) SEC-0330 or (202) 551-8090. The SEC maintains a website at www.sec.gov that contains reports, proxy and information statements and other information regarding registrants that file electronically with the SEC.

You may obtain a copy of any of our SEC filings, at no cost, by writing or telephoning us at:

The SEC allows us to “incorporate by reference” information we file with it into our registration statement of which this prospectus is a part, which means that we can disclose important information to you by referring you to other documents. The information incorporated by reference is considered to

be part of this prospectus, and information that we file later with the SEC and incorporate by reference will automatically update and supersede this information. We incorporate by reference into this prospectus the documents listed below and all future filings made by us with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, except for information “furnished” under Items 2.02, 7.01 or 9.01 on Form 8-K or other information “furnished” to the SEC which is not deemed filed and not incorporated in this prospectus, until the termination of the offering of securities described in the applicable prospectus supplement.

We will provide to each person, including any beneficial owners, to whom a prospectus is delivered, upon written or oral request of any such person, a copy of the reports and documents that have been incorporated by reference into this prospectus, at no cost. Any such request should be directed to: INC Research Holdings, Inc., 3201 Beechleaf Court, Raleigh, North Carolina 27604, Attention: Corporate Secretary (919) 876-9300. These documents are also available on the Investor Relations section of our website, which is located at http://www.incresearch.com, or as described under “Where You Can Find Additional Information” above. The reference to our website address does not constitute incorporation by reference of the information contained on our website.


	Page
ABOUT THIS PROSPECTUS SUPPLEMENT		S-2
PROSPECTUS SUPPLEMENT SUMMARY		S-3
THE OFFERING		S-5
RISK FACTORS		S-6
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS		S-12
USE OF PROCEEDS		S-15
MARKET PRICE OF OUR COMMON STOCK		S-16
DIVIDEND POLICY		S-17
SELLING STOCKHOLDERS		S-18
MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS FOR NON-U.S. HOLDERS		S-19
UNDERWRITING		S-23
LEGAL MATTERS		S-30
EXPERTS		S-30
WHERE YOU CAN FIND MORE INFORMATION		S-30
INCORPORATION OF DOCUMENTS BY REFERENCE		S-30


	Page
ABOUT THIS PROSPECTUS		1
RISK FACTORS		3
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS		4
THE COMPANY		6
USE OF PROCEEDS		6
SELLING STOCKHOLDERS		6
DESCRIPTION OF CAPITAL STOCK		7
PLAN OF DISTRIBUTION		11
LEGAL MATTERS		13
EXPERTS		13
WHERE YOU CAN FIND MORE INFORMATION		13
INCORPORATION OF DOCUMENTS BY REFERENCE		13


	High		Low
2014
Fourth Quarter (from November 7, 2014)	$	26.85	$	19.61
2015
First Quarter	$	34.54	$	22.17
Second Quarter	$	42.45	$	29.03
Third Quarter	$	51.69	$	37.53
Fourth Quarter	$	50.40	$	37.51
2016
First Quarter	$	48.13	$	34.19
Second Quarter (through April 29, 2016)	$	57.11	$	40.50


	Shares of common stock beneficially owned before this offering					Number of shares being offered		Shares of common stock beneficially owned after this offering
Name and address of beneficial owner	Number of shares		Total voting percentage			Number of shares being offered		Number of shares		Total voting percentage
Avista(1)		10,761,139		19.8	%		4,087,054		6,674,085		12.3	%
OTPP(2)		10,302,711		19.0	%		3,912,946		6,389,765		11.8	%