Relational Investors SC 13D/A PMC Sierra Inc

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934
(Amendment No. 6)*

PMC-Sierra, Inc.

(Name of Issuer)

Common Stock, $0.001 par value

(Title of Class of Securities)

69344F106

(CUSIP Number)

Ralph V. Whitworth

Relational Investors, LLC

12400 High Bluff Drive, Suite 600

San Diego, CA 92130

(858) 704-3333

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

May 13, 2015

(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. o

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.

* 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).

CUSIP No.   69344F106
	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors, LLC
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 17,307,171
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 17,307,171
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 17,307,171
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 8.75%
	14.	Type of Reporting Person (See Instructions) IA/HC/OO

2

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors Mid-Cap Fund I, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 3,508,713
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 3,508,713
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 3,508,713
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 1.77%
	14.	Type of Reporting Person (See Instructions) PN

3

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors Mid-Cap Fund II, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 6,049,025
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 6,049,025
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 6,049,025
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 3.06%
	14.	Type of Reporting Person (See Instructions) PN

4

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Fund Partners, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC/OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 39,861
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 39,861
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 39,861
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.02%
	14.	Type of Reporting Person (See Instructions) PN

5

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Coast Partners, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC/OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 433,203
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 433,203
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 433,203
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.22%
	14.	Type of Reporting Person (See Instructions) PN

6

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) RH Fund 1, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC/OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 387,763
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 387,763
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 387,763
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.20%
	14.	Type of Reporting Person (See Instructions) PN

7

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors IX, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 496,892
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 496,892
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 496,892
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.25%
	14.	Type of Reporting Person (See Instructions) PN

8

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors XV, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 460,718
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 460,718
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 460,718
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.23%
	14.	Type of Reporting Person (See Instructions) PN

9

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors XVI, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 205,587
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 205,587
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 205,587
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.10%
	14.	Type of Reporting Person (See Instructions) PN

10

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors XX, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC/OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 415,660
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 415,660
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 415,660
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.21%
	14.	Type of Reporting Person (See Instructions) PN

11

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors XXIII, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC/OO
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 582,575
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 582,575
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 582,575
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.29%
	14.	Type of Reporting Person (See Instructions) PN

12

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Relational Investors XXIV, L.P.
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) WC
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization Delaware
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power 63,836
			8.	Shared Voting Power -0-
			9.	Sole Dispositive Power 63,836
			10.	Shared Dispositive Power -0-
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 63,836
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 0.03%
	14.	Type of Reporting Person (See Instructions) PN

13

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) Ralph V. Whitworth
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) NA
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power -0-
			8.	Shared Voting Power 17,307,171
			9.	Sole Dispositive Power -0-
			10.	Shared Dispositive Power 17,307,171
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 17,307,171
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 8.75%
	14.	Type of Reporting Person (See Instructions) IN

14

	1.	Names of Reporting Persons. I.R.S. Identification Nos. of Above Persons (Entities Only) David H. Batchelder
	2.	Check the Appropriate Box if a Member of a Group (See Instructions)
		(a)			x
		(b)			o
	3.	SEC Use Only
	4.	Source of Funds (See Instructions) NA
	5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)  o
	6.	Citizenship or Place of Organization United States
Number of Shares Beneficially Owned by Each Reporting Person With			7.	Sole Voting Power -0-
			8.	Shared Voting Power 17,307,171
			9.	Sole Dispositive Power -0-
			10.	Shared Dispositive Power 17,307,171
	11.	Aggregate Amount Beneficially Owned by Each Reporting Person 17,307,171
	12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)o
	13.	Percent of Class Represented by Amount in Row (11) 8.75%
	14.	Type of Reporting Person (See Instructions) IN

15

Item 1.

Security and Issuer

This Schedule 13D/A constitutes the sixth amendment to the Schedule 13D originally filed by the Reporting Persons with the Securities and Exchange Commission (the “SEC”) on January 17, 2012 and amended by Amendment No. 1, No. 2, No. 3, No. 4 and No. 5 filed by the Reporting Persons with the SEC on November 9, 2012, January 11, 2013, August 1, 2013, February 28, 2014 and May 11, 2015 (the “Statement”) with respect to the common stock, $0.001 par value (the “Shares”), of PMC-Sierra, Inc. (the “Issuer” or the “Company”). Except as specifically amended by this Schedule 13D/A, the Statement remains in full force and effect.

Item 3. Source and Amount of Funds or Other Consideration

The Reporting Persons purchased an aggregate of 17,307,171 Shares for total consideration (including brokerage commissions) of $117.9 million derived from their working capital.

Item 4. Purpose of Transaction

Item 4 is hereby amended and supplemented as follows:

On May 13, 2015, the Issuer entered into a stock repurchase agreement (the “Stock Repurchase Agreement”) with Relational Investors LLC and certain of its affiliates (collectively, “Relational”) pursuant to which the Issuer agreed to purchase 5,500,348 Shares from Relational at a price of $8.16075 per share, for a total purchase price of approximately $44,886,965. The purchase of the shares was completed on May 14, 2015.

Pursuant to the Stock Repurchase Agreement, the Issuer has agreed to repurchase the shares of common stock at a 2.5% discount to the last closing price per share of the Issuer’s common stock on May 13, 2015, the date the agreement was entered into. Pursuant to the Stock Repurchase Agreement, Relational has agreed to certain restrictions on additional sales of Shares, including that Relational will not (a) sell or otherwise dispose of any additional PMC common stock to any entity until the first business day after the Issuer makes its second quarter earnings announcement, but no later than July 31, 2015 (the “Restrictions End Date”) or (b) sell or otherwise dispose of 3% or more shares of outstanding Shares to any entity that is required, or would by virtue of such sale become required, to file a Schedule 13D with the Securities and Exchange Commission with respect to the Issuer’s securities, until the first anniversary of the Restrictions End Date, subject to certain exceptions.

The foregoing description of the Stock Repurchase Agreement is not complete and is subject to, and qualified in its entirety by the full text of the Stock Repurchase Agreement, which is attached as an Exhibit and incorporated herein by reference.

16

Item 5. Interest in Securities of the Issuer

(a) As of the date of this Statement, the Reporting Persons beneficially own in the aggregate 17,307,171 Shares, constituting approximately 8.75% of the outstanding Shares. The percentage of Shares owned is based upon 197,891,832 Shares reported to be outstanding on April 29, 2015, as set forth in the Company’s Annual Report on Form 10-Q for the period ended March 28, 2015. The Reporting Persons may be deemed to have direct beneficial ownership of the Shares as follows:

NAME	NUMBER OF SHARES	% OF OUTSTANDING SHARES	VOTING AND DISPOSITIVE POWER
RILLC	4,663,338	2.36%	Sole
MC I	3,508,713	1.77%	Sole
MC II	6,049,025	3.06%	Sole
RFP	39,861	0.02%	Sole
RCP	433,203	0.22%	Sole
RH 1	387,763	0.20%	Sole
RI IX	496,892	0.25%	Sole
RI XV	460,718	0.23%	Sole
RI XVI	205,587	0.10%	Sole
RI XX	415,660	0.21%	Sole
RI XXIII	582,575	0.29%	Sole
RI XXIV	63,836	0.03%	Sole

RILLC, individually and in its capacity as an investment adviser, may be deemed to possess direct beneficial ownership of the 4,663,338 Shares that are owned by it and the Managed Accounts. Additionally, RILLC, as the sole general partner, of each of Relational LPs may be deemed to beneficially own (as that term is defined in Rule 13d-3 under the Securities Exchange Act of 1934, as amended) the 12,643,833 Shares beneficially owned by the Relational LPs because the limited partnership agreements of the Relational LPs specify that RILLC has sole investment discretion and voting authority with respect to those Shares. Each of Messrs. Whitworth and Batchelder, as Principals of RILLC, may be deemed to have indirect beneficial ownership of the Shares which RILLC may beneficially own. Each of Messrs. Whitworth and Batchelder disclaims beneficial ownership of such Shares except to the extent of his pecuniary interest therein.

To the best of the knowledge of each of the Reporting Persons, other than as set forth above, none of the persons named in Item 2 is the beneficial owner of any Shares.

(b) See item (a) above.

(c) On May 13, 2015, pursuant to the Stock Repurchase Agreement, the Relational Persons sold 5,500,348 Shares at a price per share of $8.16075 to the Issuer.  The sale was completed on May 14, 2015.

(d) No other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares covered by this Statement, except that dividends from, and proceeds from the sale of, the Shares held by accounts managed by RILLC may be delivered to such accounts.

(e) Not applicable.

Item 7. Material to be Filed as Exhibits

Item 7 is hereby supplemented as follows:

Exhibit D — Stock Repurchase Agreement among Issuer, Relational and certain affiliates of Relational, dated as of May 13, 2015.

(incorporated by reference to Exhibit 99.1 to Issuer’s Current Report on Form 8-K dated May 14, 2015)

17

Signature

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated:  May 14, 2015

RELATIONAL INVESTORS MID-CAP FUND I, L.P.
RELATIONAL INVESTORS MID-CAP FUND II, L.P.
RELATIONAL COAST PARTNERS, L.P.

RELATIONAL FUND PARTNERS, L.P.

RH FUND 1, L.P.

RELATIONAL INVESTORS IX, L.P.

RELATIONAL INVESTORS XV, L.P.

RELATIONAL INVESTORS XVI, L.P.

RELATIONAL INVESTORS XX, L.P.

RELATIONAL INVESTORS XXIII, L.P.

RELATIONAL INVESTORS XXIV, L.P.

By:	RELATIONAL INVESTORS, LLC
	as general partner to each,

	By:	/s/ Ralph V. Whitworth
		Ralph V. Whitworth, Principal
RELATIONAL INVESTORS, LLC
	By:	/s/ Ralph V. Whitworth
		Ralph V. Whitworth, Principal
/s/ Ralph V. Whitworth
Ralph V. Whitworth
/s/ David H. Batchelder
David H. Batchelder

18