UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

§ 240.13d-2(a)

(Amendment No. 4)¹

Hudbay Minerals Inc.

(Name of Issuer)

Common Shares, no par value

(Title of Class of Securities)

443628102

(CUSIP Number)

KANWALJIT TOOR

199 Bay Street, Suite 5050

Toronto, Ontario M5L 1E2

+1 416 504 3508

STEVE WOLOSKY, ESQ.

ANDREW FREEDMAN, ESQ.

OLSHAN FROME WOLOSKY LLP

1325 Avenue of the Americas

New York, New York 10019

(212) 451-2300

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

December 13, 2018

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ¨.

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See § 240.13d-7 for other parties to whom copies are to be sent.

1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

The following constitutes Amendment No. 4 to the Schedule 13D filed by the undersigned (“Amendment No. 4”). This Amendment No. 4 amends the Schedule 13D as specifically set forth herein.

Item 3 is hereby amended and restated to read as follows:

The Shares purchased by each of Waterton Mining LP and Waterton Fund II were purchased with working capital (which may, at any given time, include margin loans made by brokerage firms in the ordinary course of business) in open market purchases, except as otherwise noted, as set forth in Schedule A, which is incorporated by reference herein. The aggregate purchase price of the 13,560,625 Shares beneficially owned by Waterton Mining LP is approximately C$84,001,266, excluding brokerage commissions. The aggregate purchase price of the 13,560,631 Shares beneficially owned by Waterton Fund II is approximately C$84,001,303, excluding brokerage commissions.

Item 4 is hereby amended to add the following:

On December 13, 2018, WGRM Inc. and certain of its affiliates (collectively, “Waterton”) issued an open letter to the Issuer’s shareholders announcing that Waterton is finalizing its recruitment of a majority slate of highly qualified, independent director candidates, including a transformational CEO candidate, to nominate for election to the Board of Directors (the “Board”) at the Issuer’s 2019 Annual Meeting of Shareholders (the “Annual Meeting”). Waterton stated that its nominees will possess the collective experience and strategic expertise to drive value at the Issuer and address the challenges and maximize the opportunities facing the Issuer.

In the letter, Waterton reiterated its disappointment with the Issuer’s abysmal performance and the continued destruction of shareholder value under the stewardship of the Issuer’s management team and Board. Specifically, Waterton noted that for the period ending October 4, 2018, the Issuer’s total shareholder return (TSR) versus its peer group¹ was -106% during the CEO’s tenure and -134% during the Chairman’s tenure.² Waterton also noted that throughout its efforts to engage in a constructive dialogue with the Issuer, the Board and management team demonstrated a pattern of systemic bad faith and an unwillingness to meaningfully engage with shareholders. Waterton expressed concerns that the Issuer’s behavior stems from a culture of toxic, value-destructive entrenchment at both the Board and C-Suite levels. Waterton further questioned the independence of the Board, noting that 40% of the current Board has been in place for nearly a decade, including Chairman Alan Hibben, who seems to be exerting a troubling level of influence over the Board.

Additionally, in the letter, Waterton withdrew its request to call a Special Meeting relating to shareholder approvals for certain transactions so that Waterton can focus on the urgent need for Board refreshment. A copy of the letter is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

¹ Waterton believes an appropriate peer group for the Issuer should only include companies that (i) have a market capitalization of greater than US$500 million, (ii) have material exposure to the Americas, (iii) have copper comprising greater than 50% of reserves, and (iv) are publicly listed on a major stock exchange, and not the peer group described in the Issuer’s public disclosure.

² Source: Capital IQ

Items 5(a)-(c) are hereby amended and restated to read as follows:

The aggregate percentage of Shares reported owned by each person named herein is based upon 261,272,151 Shares outstanding, as of October 30, 2018, which is the total number of Shares outstanding as reported in Exhibit 99.2 to the Issuer’s Report of foreign issuer on Form 6-K filed with the Securities and Exchange Commission on November 1, 2018.

Percentage: Approximately 5.2%

Percentage: Approximately 5.2%

Percentage: Approximately 5.2%

Percentage: Approximately 5.2%

Percentage: Approximately 5.2%

Percentage: Approximately 10.4%

Percentage: Approximately 10.4%

Item 7 is hereby amended to add the following exhibit:

SIGNATURES

After reasonable inquiry and to the best of his knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: December 17, 2018

SCHEDULE A

Transactions in the Shares Since the Filing of Amendment No. 3 to the Schedule 13D

Waterton Mining Parallel Fund Offshore Master, LP

Waterton Precious Metals Fund II Cayman, LP

^* The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from C$6.14 to C$6.35. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth herein.

Exhibit 99.1

December 13, 2018

Dear Hudbay Shareholders:

Waterton Precious Metals Fund II Cayman, LP and Waterton Mining Parallel Fund Offshore Master, LP (the “Funds”), each of which are managed by Waterton Global Resource Management, Inc. (the "Investment Adviser", the Investment Adviser together with the Funds (“Waterton”)) own approximately 10% of the issued and outstanding shares of Hudbay Minerals Inc. ("Hudbay" or the "Company") (TSX:HBM) (NYSE:HBM), making us one of the Company’s largest shareholders.

In late October, Waterton requested a meeting with the Hudbay Board to discuss how the Board may be refreshed to unlock value for the Company’s shareholders. Waterton’s objective was to engage in a constructive dialogue with the Board to arrive at a mutual resolution that would provide for the level of Board change, enhanced oversight and renewed accountability and independence that we believe is required at Hudbay. In early November, we met with Chairman Alan Hibben and director Sarah Kavanagh to discuss a potential framework for the changes that are both necessary and appropriate for the Hudbay Board. Key aspects of this meeting are as follows:

Needless to say, we were naturally frustrated, but not surprised, by the Board’s arbitrary and dismissive conduct.

The Hudbay Board and management team have demonstrated a pattern of systemic bad faith and lack of engagement with shareholders. We believe that the Company’s behavior stems from a culture of toxic, value destructive, entrenchment at both the Board and C-Suite levels. Given the unfortunate and revealing about-turn after Ms. Kavanagh’s request for a Term Sheet, we further believe that Chairman Alan Hibben may be exerting a troubling level of influence over the Board during his now near decade long tenure. This concern about Mr. Hibben exerting an inappropriate and undue level of influence over the Board and management has been communicated to us by multiple long-term shareholders of Hudbay who have seen the value of their investment eroded.

Following these latest events, we reviewed the Company’s performance under its current entrenched leadership team and the results are shockingly abysmal. Hudbay’s Total Shareholders Return¹ vs its peer group² for 1 year, 3 years, 5 years, during the CEO’s tenure and during the Chairman’s tenure on the Board of Hudbay are as follows:

Total Shareholder Return

The Company’s more recent underperformance is also concerning. Hudbay currently trades at a material discount to its peer group on multiple key valuation metrics. Year to date, Hudbay's share price has declined 41.5%⁵. We believe the share price would have declined even more had (i) Waterton not purchased in excess of 26,000,000 million shares of the Company over the exchanges in the past five months, (ii) Waterton not publicly opposed the potentially value destructive Mantos Copper transaction, and (iii) Waterton not initiated the narrative of Board refreshment.

Last quarter, the Company finally announced above consensus earning numbers, but we find the timing of this quite interesting given that Waterton has recently publicly scrutinized its performance. This was only the third time in the past eleven quarters (since Alan Hair was appointed CEO) that the Company has not missed earnings consensus; we would further note that the Company has missed earnings consensus in 74% of quarters during the Chairman’s tenure.

¹ Total Shareholder Return calculated as of close October 4, 2018, the day before Waterton’s first public comments regarding Hudbay.

² We believe an appropriate peer group for Hudbay should only include companies that (i) have a market capitalization of greater than US$500 million, (ii) have material exposure to the Americas, (iii) have copper comprising greater than 50% of reserves, and (iv) are publicly listed on a major stock exchange, and not the peer group described in Hudbay’s public disclosure.

³ Period beginning January 1, 2016.

⁴ Period beginning March 25, 2009.

⁵ As at December 12, 2018.

The bottom line is this: the culture of Board and management entrenchment and underperformance at Hudbay must end to preserve shareholder value. We believe this culture change can only be implemented with a substantial reconstitution of the Hudbay Board and C-Suite.

As a result, we are pleased to report that Waterton is finalizing its recruitment of a majority slate of highly qualified director candidates, including a transformational potential CEO, to nominate for election at the 2019 Annual Meeting. As a technical matter, we are also hereby withdrawing our request to call a Special Meeting relating to shareholder approvals for certain transactions.

Our focus will now squarely be on the issue that a number of shareholders have communicated to us as being absolutely urgent and integral: ending the nearly decade long malaise, ineptitude and entrenchment at Hudbay so that the Company can be rebuilt and substantial value can be created for Hudbay stakeholders.

The Board changes we expect to propose to Hudbay shareholders will provide fresh perspectives and the objectivity to make difficult decisions without the burden of attachment to past practices, decisions or allegiances. With 40% of the current Hudbay Board having been in place for nearly a decade, including the Chairman of the Board, who seemingly dominates the boardroom, we question the degree of real independence on this Board. Our campaign to refresh the Hudbay Board is certainly driven by this Board’s questionable decision making and resulting value destruction; importantly, however, it is also a referendum on meaningful independence at a public company, a key tenet of good corporate governance.

We are pleased to report that, subject to the finalization of our director recruitment process, 100% of our director nominees will be, rather exceptionally, independent of Waterton. Waterton has no desire to obtain a Board seat for Waterton itself; as one of the Company’s largest shareholders, however, we do plan to be fierce and active advocates for real independence in the boardroom to ensure that our investment is adequately protected and substantial value is created for all stakeholders. At the same time, we are also continuing to carefully and prudently assess the issue of selective continuity on the Board.

We are confident that once finalized you will be presented with a team of extremely well-qualified professionals including a potential CEO candidate possessing the key characteristic that matters most to shareholders: a proven track record of creating shareholder value in this sector. Our potential director candidates are being recruited because they are uniquely positioned to address the challenges and maximize the opportunities facing the Company. We believe our nominees will possess the collective experience and strategic expertise to drive value at Hudbay and restore shareholder confidence in the Board’s ability to select an effective leadership team and to hold senior management accountable through diligent oversight.

We believe that the following are critical attributes that a refreshed Hudbay Board must possess, and expect that our ultimate nominees will be strongly positioned in these areas:

We expect that Hudbay will duly schedule the 2019 Annual Meeting in accordance with the early-to-mid May timeframe in which it has consistently held its annual meetings over the past five years. We further expect the Hudbay Board to refrain from any material transaction that may impact the future of the Company until the 2019 Annual Meeting and we can provide comfort to all shareholders that we will access all available remedies to ensure that the Company does not engage in any value destructive transactions before you have the ability to voice your views through your votes.

We expect to finalize our director nominees within the next few weeks and we are excited to socialize such nominees with our fellow shareholders very early in the New Year. We firmly believe that with the right senior leadership in place, an appropriate alignment of interests and a robust governance structure, there is a bright future ahead for Hudbay’s shareholders.

We look forward to engaging with you as we approach the 2019 Annual Meeting.

Sincerely,

Isser Elishis

Chief Investment Officer