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FOR IMMEDIATE RELEASE

ATTENTION: FINANCIAL AND BUSINESS EDITORS
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NBT Contact:  Daryl R. Forsythe         CNB Contact:       Donald L. Brass
                   607-337-6416                            518-673-3243


                                                  Pursuant to Rule 425 under the
                                               Securities Act of 1933 and deemed
                                             filed pursuant to Rule 14a-12 under
                                            the Securities Exchange Act of 1934.


                         NBT BANCORP, CNB FINANCIAL CORP
                            ANNOUNCE MERGER AGREEMENT

    NORWICH, NY and CANAJOHARIE, NY (June 19, 2001) - NBT Bancorp Inc. (NBT)
(NASDAQ: NBTB) and CNB Financial Corp. (CNB) (NASDAQ: CNBF) announced today that
they have entered into a definitive agreement providing for the merger of CNB
with and into NBT. The merger, which has been unanimously approved by the boards
of directors of NBT and CNB, is subject to regulatory approvals as well as
approval by each company's shareholders and is expected to close in the fourth
quarter of 2001.

    Under the terms of the agreement, CNB stockholders will receive 1.2 shares
of NBT common stock for each share of CNB common stock. The transaction is
structured as a tax-free exchange of shares to be accounted for as a pooling of
interests. Based upon NBT's closing share price on June 18, 2001, the
transaction values each CNB share at $18.30. The total transaction is valued at
$140 million. CNB Chairman Van Ness D. Robinson, Vice Chairman John P. Woods and
Director Joseph A. Santangelo will join the NBT Board of Directors upon
completion of the merger. Cost savings have been identified that NBT expects
will make the proposed merger accretive to NBT earnings per share on a quarterly
basis beginning in 2002.

    The merger agreement provides for the merger of CNB's subsidiary, Central
National Bank, into NBT's bank subsidiary NBT Bank, N.A. NBT Bank is a
full-service commercial bank formed in 1856 and is headquartered in Norwich, NY.
Central National Bank is a full-service commercial bank headquartered in
Canajoharie, NY. Formed in 1855, Central National Bank conducts business from 29
community bank offices in nine Upstate New York counties, including Chenango,
Fulton, Herkimer, Montgomery, Oneida, Otsego, Saratoga, Schenectady and
Schoharie.



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    Upon completion of the merger, Central National Bank will become a division
of NBT Bank. This newly created division will retain the Central National Bank
name and headquarters in Canajoharie. NBT President and CEO Daryl R. Forsythe
commented, "We employed a similar strategy with Pennstar Bank, the Pennsylvania
division of NBT Bank, during the first quarter of 2001 and are already beginning
to see the benefits. We have successfully streamlined our operations while
maintaining the local decision making and high service levels that are essential
elements of our community banking philosophy."

    In addition, CNB is rescinding its previously announced Common Stock
Repurchase Program that was announced on February 23, 2001.

     CNB Chairman Robinson stated, "We are thrilled to have this opportunity to
partner with NBT. This merger will enable Central National Bank to continue to
deliver high quality products and service to our customers with a focus on
community banking."

    Peter J. Corso, currently Central National Bank's Executive Vice President
and Chief Financial Officer, will serve as president and chief operating officer
of the new banking division. CNB President and CEO Donald L. Brass has announced
that he will retire following the completion of the merger and integration
process. NBT Chairman Forsythe stated, "We are pleased that Don Brass will
continue to offer his leadership and expertise during this important process."
CNB President Brass added, "This merger represents a great strategic opportunity
for our organizations, and I am excited to help to lay the foundation for its
success."

    NBT and CNB will host a teleconference regarding the transaction on June 20,
2001 at 4:00 PM (Eastern Daylight Time). Investors, analysts and other
interested parties may dial into the teleconference at 1-800-895-7761. In
addition, a live webcast including the slide presentation pertaining to the
teleconference will be accessible at www.nbtbank.com.

    Prior to this announcement, both NBT and CNB have been engaged in efforts to
strategically grow their respective companies. In 2000, NBT acquired two
community banks in Northeastern Pennsylvania, LA Bank, N.A. and Pioneer American
Bank, N.A. These institutions, along with two branches acquired from Mellon Bank
and six acquired from Sovereign Bank, were merged during the fourth quarter to
create Pennstar Bank. In 2000, NBT also acquired M. Griffith, Inc., a registered
broker-dealer based in Utica, NY providing a variety of investment and financial
planning services. NBT Bank's presence expanded in 2000 with the addition of a
commercial banking office in Albany. NBT completed a merger with First National
Bancorp, Inc. on June 1, 2001. This merger also included NBT Bank's acquisition
of the six offices of the First National Bank



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of Northern New York. These banking locations are continuing to operate as
offices of the First National Bank of Northern New York until the systems
conversion is completed in late July.

    CNB has grown Central National Bank from 19 branches in the second quarter
of 1999 to 29 branches at the end of the first quarter of 2000. In the second
half of 1999, locations were added in Clifton Park, Herkimer and Whitesboro, NY.
Locations in Halfmoon and Saratoga Springs, NY were added in the first quarter
of 2000. In 2000, CNB also acquired five branches from Astoria Federal Savings
and Loan Association with one each in Cooperstown and Norwich and three in
Oneonta.

     NBT is a financial services holding company headquartered in Norwich, NY
with combined assets of $2.6 billion at March 31, 2001. The company currently
operates through three full-service community banking divisions and a financial
services company, including NBT Bank with 37 locations serving Central and
Northern New York, First National Bank of Northern New York with six locations,
Pennstar Bank with 40 locations in Northeastern Pennsylvania, and NBT Financial
Services, Inc., which includes M. Griffith, Inc. and Pennstar Financial
Services, Inc.

     CNB is headquartered in Canajoharie, NY and had assets of $964 million at
March 31, 2001. In addition to Central National Bank, CNB is the holding company
for Central Asset Management, a provider of investment advisory services.

FORWARD-LOOKING STATEMENTS: This news release contains forward-looking
statements. These forward-looking statements involve risks and uncertainties and
are based on the beliefs and assumptions of our management team and our
subsidiaries and on the information available to management at the time that
these statements were made. There are a number of factors, many of which are
beyond our control, that could cause actual conditions, events or results to
differ significantly from those described in the forward-looking statements.
Factors that may cause actual results to differ materially from those
contemplated by such forward-looking statements include, among others, the
following possibilities: (1) regulatory approvals and clearances and other
prerequisites to the merger of NBT and CNB may not be obtained, or may be
received outside of expected time frames or be received subject to unacceptable
conditions; (2) competitive pressures among depository and other financial
institutions may increase significantly; (3) competitors may have greater
financial resources and develop products that enable such competitors to compete
more successfully than NBT and CNB; (4) revenues may be lower than expected; (5)
changes in the interest rate environment may reduce interest margins; (6)
general economic conditions, either nationally or regionally, may be less
favorable than expected, resulting in, among other things, a deterioration in
credit quality and/or a reduced demand for credit; (7) legislative or regulatory
changes, including changes in accounting standards, may adversely affect the
businesses in which NBT and CNB are engaged; (8) costs or difficulties related
to the integration of the businesses of NBT and CNB and their merger



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partners may be greater than expected; (9) expected cost savings associated with
the merger of NBT and CNB or with recent mergers and acquisitions may not be
fully realized or realized within the expected time frames; (10) deposit
attrition, customer loss, or revenue loss following the merger of NBT and CNB or
other recent mergers and acquisitions may be greater than expected; and (11)
adverse changes may occur in the securities markets or with respect to
inflation. Forward-looking statements speak only as of the date they are made.
We do not undertake to update forward-looking statements to reflect subsequent
circumstances or events.

     This news release may be deemed to be solicitation material in respect of
the proposed merger of CNB Financial Corp. (CNB) with NBT Bancorp Inc. (NBT)
pursuant to an Agreement and Plan of Merger, dated as of June 19, 2001, by and
between NBT and CNB (the Agreement). Filing of this news release is being made
in connection with Regulation of Takeovers and Security Holder Communications
(Release No. 33-7760, 34-42055) promulgated by the Securities and Exchange
Commission (SEC).

    NBT and its directors and executive officers may be deemed to be
participants in the solicitation of proxies in respect of the transactions
contemplated by the Agreement. These directors and executive officers include
the following: Daryl R. Forsythe, Michael J. Chewens, Martin A. Dietrich, David
E. Raven, J. Peter Chaplin, Richard Chojnowski, Gene E. Goldenziel, Peter B.
Gregory, William C. Gumble, Bruce D. Howe, Andrew S. Kowalczyk, Jr., John G.
Martines, John C. Mitchell, Joseph G. Nasser, William L. Owens and Paul O.
Stillman. As of May 31, 2001, these directors and executive officers
beneficially owned in the aggregate 1,625,226 shares, or approximately 6.81% of
NBT's outstanding common stock. Additional information about the directors and
executive officers of NBT is included in NBT's proxy statement for its 2001
Annual Meeting of Shareholders dated March 26, 2001.

    CNB and its directors and executive officers may be deemed to be
participants in the solicitation of proxies in respect of the transactions
contemplated by the Agreement. These directors and executive officers include
the following: Van Ness D. Robinson, Donald L. Brass, Peter J. Corso, Michael D.
Hewitt, J. Carl Barbic, Joseph A. Santangelo and John P. Woods, Jr., William J.
Querbes, Thomas Giglio and Albert A. Petitti. As of May 31, 2001, these
directors and executive officers beneficially owned in the aggregate 1,323,461
shares, or approximately 17.83% of CNB's outstanding common stock. Additional
information about the directors and executive officers of CNB is included in
CNB's proxy statement for its 2001 Annual Meeting of Shareholders dated April 3,
2001.

    In conjunction with the proposed merger, NBT will file with the SEC a
registration statement on SEC Form S-4. The registration statement will contain
a joint proxy statement/prospectus, which describes the proposed merger of NBT
and CNB and the proposed terms and conditions of the merger. Stockholders of NBT
and CNB are encouraged to read the registration statement after it is filed and
the joint proxy statement/prospectus contained in the registration statement,
because these documents will contain important information about the merger. The
registration statement, including the joint proxy statement/prospectus, will be
available for free, both on the SEC's web site (www.sec.gov) or by contacting
NBT Bancorp Inc., Attention: Michael J. Chewens, 52 South Broad Street, Norwich,
New York 13815, telephone 607-337-6520; or CNB Financial Corp., Attn: Holly C.
Craver, 24 Church Street, Canajoharie, New York 13317, telephone 518-673-3243.

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