SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                            ------------------------

                                    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.
-------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)


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

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

Registrant's telephone number, including area code       607/337-2265
                                                    ---------------------

                                       N/A
       ------------------------------------------------------------------
          (Former Name or Former Address, if Changed Since Last Report)
<PAGE>

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).





<PAGE>



                                   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






<PAGE>



                                  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).
[{"type": "8-K", "sequence": "1", "description": "FORM 8-K", "secsgml_size_bytes": 5275}]
{"company-data": {"conformed-name": "NBT BANCORP INC", "cik": "0000790359", "assigned-sic": "6021", "irs-number": "161268674", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "000-14703", "film-number": "99778722"}, "business-address": {"street1": "52 S BROAD ST", "city": "NORWICH", "state": "NY", "zip": "13815", "phone": "6073376000"}, "mail-address": {"street1": "52 S. BROAD STREET", "city": "NORWICH", "state": "NY", "zip": "13815"}}
SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                            ------------------------

                                    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.
-------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)

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

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

Registrant's telephone number, including area code       607/337-2265
                                                    ---------------------

                                       N/A
       ------------------------------------------------------------------
          (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).