UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Item 1.

Security and Issuer

This Amendment No. 6 to the Schedule 13D amends and supplements the Schedule 13D, as amended by Amendment No. 5 to the Tender Offer Statement on Schedule TO filed on October 8, 2010, Amendment No. 2 to  the Schedule 13D filed on October 15, 2010, Amendment No. 3 to the Schedule 13D filed on October 22, 2010, Amendment No. 6 to the Tender Offer Statement on Schedule TO filed on October 25, 2010 and Amendment No. 7 to the Tender Offer Statement on Schedule TO filed on October 27, 2010 (the “Schedule 13D”), originally filed on August 29, 2010 by 3M Company and its wholly-owned subsidiary Ventura Acquisition Corporation (collectively, the “Reporting Persons”) with respect to the common stock, par value $0.001 per share (the “Shares”), of Cogent, Inc. (“Cogent” or the “Issuer”).

Unless otherwise indicated, all capitalized terms used herein but not defined herein shall have the same meaning as set forth in the Schedule 13D.

Item 4.

Purpose of Transaction

Item 4 of the Schedule 13D is hereby amended and supplemented by adding the following:

Following a shareholder vote on December 1, 2010, at which holders of a majority of the Shares voted to approve and adopt the Merger Agreement, 3M completed its acquisition of Cogent via the merger of Purchaser with and into Cogent with Cogent (the “Surviving Corporation”) becoming a wholly owned subsidiary of 3M. As a result of the effectiveness of the merger and the transactions contemplated by the Merger Agreement, the Issuer is now a wholly owned subsidiary of 3M, and with no public market for the Issuer’s stock, price quotations with respect to sales of the Issuer’s stock in the public market are no longer available, registration of the Issuer’s Common Stock under the federal securities laws will be terminated, and the Issuer is no longer required to file periodic reports with the United States Securities and Exchange Commission.

At the effective time of the Merger, (1) each issued and outstanding Share (other than Shares held in the treasury of Cogent or owned by the Reporting Persons, or by any direct or indirect wholly owned subsidiary of the Reporting Persons or Cogent, in each case immediately prior to the effective time of the Merger and any Shares that are issued and outstanding immediately prior to the effective time of the Merger and held by a Cogent stockholder who is entitled to demand and properly demands appraisal of such Shares) was, by virtue of the Merger and without any action on the part of the Reporting Persons or the Issuer or the holder, cancelled and converted into the right to receive $10.50 in cash, without interest thereon and less any required withholding taxes; (2) all Shares held by the Reporting Persons or any wholly owned subsidiary of the Reporting Persons or the Issuer and Shares held by the Issuer in treasury were cancelled and no payment or distribution was made with respect to such Shares; (3) each share of Purchaser common stock issued and outstanding immediately prior to the effective time was, by virtue of the merger and without any action on the part of the holder thereof, converted into a share of the Surviving Corporation, making Cogent a wholly owned subsidiary of 3M; (4) the certificate of incorporation of the Surviving Corporation was amended to conform with Exhibit B of the Merger Agreement; (5) the bylaws of the Surviving Corporation were amended to read as the bylaws of Purchaser as in effect immediately prior to the effective time of the Merger, except that such bylaws were amended to reflect that the name of the Surviving Corporation is 3M Cogent, Inc. and (6) the directors of Purchaser became the directors of the Surviving Corporation and the officers of the Issuer immediately prior to the effective time became the initial officers of the Surviving Corporation.

Item 5.

Interest in Securities of the Issuer

Item 5 of the Schedule 13D is hereby amended, in pertinent part, as follows:

(a) — (b) As a result of the Merger, 3M is the direct record owner of, and has the power to vote and to dispose or direct the disposition of 100 shares of the Surviving Corporation, which represent 100% of the Surviving Corporation’s outstanding shares.

3M Company

By:

/s/ Gregg M. Larson

Name:

Gregg M. Larson

Title:

Deputy General Counsel and Secretary