SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


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                                    FORM 8-K

                                 CURRENT REPORT
                       PURSUANT TO SECTION 13 OR 15(D) OF
                       THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported):  December 16, 1999

                                NBT BANCORP INC.
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             (Exact name of registrant as specified in its charter)


   Delaware                       0-14703                      16-1268674
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(State or Other               Commission File No.            (I.R.S. Employer
Jurisdiction of                                             Identification No.)
Incorporation)

          52 South Broad Street, Norwich, New York                    13815
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         (Address of Principal Executive Offices)                  (Zip Code)

Registrant's telephone number, including area code       607/337-2265
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                                       N/A
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          (Former Name or Former Address, if Changed Since Last Report)

ITEM 5. OTHER EVENTS. On November 15, 1994, the Board of Directors of the Registrant declared a dividend distribution of one Right for each outstanding share of Registrant's Common Stock to stockholders of record at the close of business on November 15, 1994. See the Registrant's Form 8-A, dated November 29, 1994, for a complete description of the Rights Agreement between the Registrant and American Stock Transfer Trust Company (the "Rights Agreement"), as Rights Agent (the "Rights Agent"). Since adoption of the Rights Agreement, new certificates for the Registrant's Common Stock issued after November 15, 1994, contained a notation incorporating the Rights Agreement by reference. At a special meeting of the Registrant's Board of Directors held on November 22, 1999, the Board adopted amendments to the Rights Agreement. These amendments were occasioned by a decision of the Delaware Supreme Court in a case not involving the Registrant that invalidated the delayed redemption provision in a stockholder rights plan. The Rights Agreement contains such a "continuing directors" feature that would be invalid under Delaware law in view of the Court's decision. Additionally, the Rights Agreement provides in a "permitted transaction" exception that only directors who are not officers of the Registrant and who are not representatives, nominees, affiliates, or associates of an Acquiring Person, as defined, may make a decision whether a transaction is a Permitted Transaction. This provision is of questionable validity in view of the Delaware court decision. Accordingly, the Registrant's Board of Directors has determined to adopt amendments to the Rights Agreement that will eliminate both the continuing directors and permitted transaction features of the Rights Agreement. The amendments were adopted by the Registrant and the Rights Agent on December 16, 1999. ITEM 7. FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS. 4.1 Rights Agreement, dated as of November 15, 1994, between NBT Bancorp Inc. and American Stock Transfer Trust Company as Rights Agent (incorporated herein by reference to Exhibit 4.1 of the Registrant's Form 8- A, dated November 25, 1994, File No. 0-14703). 4.2 Amendment to Rights Agreement, dated as of December 16, 1999 between NBT Bancorp Inc. and American Stock Transfer Trust Company (filed herewith).

SIGNATURES Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, the Registrant has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized. NBT BANCORP INC. By: /s/ Michael J. Chewens ---------------------- Michael J. Chewens Executive Vice President and Chief Financial Officer Date: December 21, 1999

EXHIBIT INDEX 4.2 Amendment to Rights Agreement, dated as of December 16, 1999 between NBT Bancorp Inc. and American Stock Transfer Trust Company (filed herewith).


                                   EXHIBIT 4.2


                          AMENDMENT TO RIGHTS AGREEMENT


         AMENDMENT  dated as of  December  16, 1999 (this  "Amendment"),  to the
RIGHTS  AGREEMENT dated as of November 15, 1994 (the  "Agreement"),  between NBT
Bancorp  Inc.,  a Delaware  corporation  (the  "Company"),  and  American  Stock
Transfer Trust Company (the "Rights Agent").

         WHEREAS, the Company and the Agent have entered into the Agreement at
the direction of the Company; and

         WHEREAS, the Company has directed that the Agreement be amended; and

         WHEREAS,  the  Distribution  Date (as defined in the Agreement) has not
occurred and the  penultimate  sentence of Section 26(a) of the Agreement is not
applicable to this Amendment; and

         WHEREAS, on November 22, 1999 the Board of Directors resolved to amend
the Rights Agreement;

         NOW, THEREFORE, the Agreement is amended as follows (terms used and not
defined herein have the meanings as defined in the Agreement):

         1.       Section 1 (k) of the Agreement is amended in its entirety to
read as follows:

                  (k) [Intentionally Omitted]

         2. Section 1 (w) of the Agreement is amended in its entirety to read as
follows:

                  (w) [Intentionally Omitted]

         3. Section 11  (a)(ii)(B)  of the  Agreement is amended by deleting the
words "or a Permitted Transaction."

         4. Section 11  (a)(ii)(D)  of the  Agreement is amended by deleting the
words "Continuing Directors" in clause (y) thereof and inserting in lieu thereof
the words "directors of the Company."

         5. Section 13(e) of the Agreement is hereby deleted.

         6.  Section  23(a)(i) of the  Agreement  is amended by (a) deleting the
proviso in the first sentence thereof in its entirety;  (b) deleting subsections
(a)(ii) and (a)(iii) thereof, and (c) renumbering  subsection (a)(iv) thereof as
(a)(ii).


7. Section 26 of the Agreement is amended by deleting (a) the words "who became such other than pursuant to a Permitted Transaction," (b) the words "who becomes such other than pursuant to a Permitted Transaction," and (c) in its entirety the final proviso of the second sentence of such section. 8. The form of Rights Certificate set forth as Exhibit B to the Agreement is amended by deleting the following proviso: "provided that with certain exceptions the Corporation shall be entitled so to redeem the Rights only if the Board of Directors consists of a majority of continuing Directors (as such term is defined in the Rights Agreement)." 9. Except as modified hereby, the Agreement remains in full force and effect. 10. The provisions of Sections 27, 29, 30, 31, and 33 of the Agreement shall apply to this Amendment as if set forth herein. IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed as of the day and year first above written. NBT BANCORP INC. By: /s/ DARYL R. FORSYTHE -------------------- Daryl R. Forsythe President and Chief Executive Officer AMERICAN STOCK TRANSFER TRUST COMPANY, as Rights Agent By: /s/ HERBERT J. LEMMER -------------------- Herbert J. Lemmer Vice President