UNITED STATES 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): September 7, 2005

                               CALPINE CORPORATION

                            (A Delaware Corporation)

                        Commission file number: 001-12079

                  I.R.S. Employer Identification No. 77-0212977

                           50 West San Fernando Street
                           San Jose, California 95113
                            Telephone: (408) 995-5115

Check  the  appropriate  box  below  if the  Form  8-K  filing  is  intended  to
simultaneously  satisfy the filing obligation of the registrant under any of the
following provisions:

[ ]  Written communications pursuant to Rule 425 under the Securities Act
     (17 CFR 230.425)

[ ]  Soliciting material pursuant to Rule 14a-12 under the Exchange Act
     (17 CFR 240.14a-12)

[ ]  Pre-commencement communications pursuant to Rule 14d-2(b) under the
     Exchange Act (17 CFR 240.14d-2(b))

[ ]  Pre-commencement communications pursuant to Rule 13e-4(c) under the
     Exchange Act (17 CFR 240.13e-4(c))




ITEM 1.01 -- ENTRY INTO A MATERIAL DEFINITIVE AGREEMENT

     On September 7, 2005,  Calpine  Corporation  ("Calpine")  and its indirect,
wholly owned subsidiary  Calpine Energy Services,  L.P. ("CES"),  entered into a
Master  Transaction  Agreement (the "Agreement") with The Bear Stearns Companies
Inc. ("Bear  Stearns").  At the closing of the transactions  contemplated by the
Agreement (the "Closing"),  Calpine Merchant Services Company, Inc., an indirect
wholly owned  subsidiary of Calpine  ("CMSC") and CalBear Energy LP, an indirect
wholly owned subsidiary of Bear Stearns  ("CalBear") will also become parties to
the  Agreement.  Pursuant  to  the  terms  of the  Agreement,  Calpine  and  its
Affiliates,  on the one hand, and Bear Stearns and its Affiliates,  on the other
hand,  will each refer certain  trades and third party service  transactions  to
CalBear. This referral obligation does not include any transaction that could be
serviced by, used by, hedge cash flow from or otherwise  optimize the results or
flexibility  of the assets of the  referring  entity.  In addition,  none of the
parties will enter into a venture that substantially replicates the transactions
contemplated by the Agreement  during the term of the Agreement and for a period
of up to two years after the  termination of the  Agreement,  depending upon the
reason for the termination.

     Calpine has  guaranteed the payment in full when due of all amounts owed by
and due from CES or CMSC to Bear Stearns or CalBear pursuant to the terms of the
Agreement or any of the  agreements  (described  below) to be entered into under
the  Agreement.  Bear Stearns has guaranteed the payment in full when due of all
amounts  owed by and due from  CalBear to Calpine,  CES or CMSC  pursuant to the
terms of the  Agreement  or any of the  agreements  to be entered into under the
Agreement.  In  addition,  Bear  Stearns has agreed to provide  CalBear with all
funds and  collateral  necessary  for CalBear to perform its  obligations  under
certain agreements and to provide certain other financial support to CalBear.

     The  Closing is subject to certain  conditions,  including  the  receipt of
regulatory  approval  from the FERC and the  execution  and  delivery of certain
agreements,  including  an Agency and  Services  Agreement by and among CMSC and
CalBear,  pursuant to which CMSC will act as CalBear's  exclusive  agent for gas
and power  trading;  a Trading  Master  Agreement  by and  among  CES,  CMSC and
CalBear,  pursuant to which CalBear will execute  credit  enhancement  trades on
behalf of CES; and an ISDA Master Agreement,  Schedule,  and applicable  annexes
between CES and CalBear to effectuate the credit enhancement trades. Pursuant to
the Agency and  Services  Agreement,  CSMC will earn  service fees (a portion of
which  will be held in  reserve  during  the  term of the  Agency  and  Services
Agreement) equal to 50% of CalBear's profits, which fees (including the reserve)
are subject to a requirement to return based on losses at CalBear,  up to 50% of
such losses.

     The Agreement  and the  agreements  entered into under the  Agreement  will
terminate on November  30, 2006 unless both Calpine and Bear Stearns  affirm the
continuation  of the Agreement  upon 90 days' advance  notice to the other,  and
will terminate at the end of each calendar quarter thereafter unless extended by
both  parties.  In addition,  both Calpine and Bear  Stearns may  terminate  the
Agreement  voluntarily  upon 90 days' advance  written  notice and for specified
causes.

     Calpine,  CES and CMSC, on one hand,  and Bear Stearns and CalBear,  on the
other  hand,  each  indemnify  the others  against any  damages  resulting  from
inaccuracy  of  representations,   breach  of  covenant  or  agreement,  willful
misconduct, brokerage fees, and violation of laws, subject to certain carve-outs
and limitations.


ITEM 9.01 FINANCIAL STATEMENTS AND EXHIBITS

(a)  Financial Statements of Businesses Acquired.

     Not  Applicable

(b)  Pro Forma Financial Information.

     Not  Applicable

(c)  Exhibits.

     99.1 Press Release dated September 8, 2005.



                                   SIGNATURES

Pursuant  to the  requirements  of the  Securities  Exchange  Act of  1934,  the
registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned hereunto duly authorized.


                                  CALPINE CORPORATION



                                  By:  /s/ Robert D. Kelly
                                       ------------------------------------
                                       Robert D. Kelly
                                       Executive Vice President and
                                       Chief Financial Officer

Date: September 13, 2005




                                  EXHIBIT INDEX




                     Exhibit                Description
                     -------   -------------------------------------
                     99.1      Press release dated September 8, 2005


================================================================================

EXHIBIT 99.1



For Immediate Release


      BEAR STEARNS AND CALPINE FORM ENERGY MARKETING AND TRADING VENTURE:
                                 CALBEAR ENERGY


     (NEW YORK, NY)  /BusinessWire  - First Call / September 8, 2005 -- The Bear
Stearns Companies Inc. [NYSE: BSC] and Calpine Corporation [NYSE: CPN] announced
today that they have agreed to form a new energy  marketing and trading  venture
to develop a significant  customer  business focused on physical natural gas and
power trading and related structured transactions.  CalBear Energy LP (CalBear),
a wholly  owned  Bear  Stearns  subsidiary,  will  benefit  from  the  financial
resources,   risk  management  expertise  and  client  reach  of  Bear  Stearns,
complimented by the market knowledge, technology, trading ability, deal flow and
customers  of  Calpine.  These  strengths  will  provide a solid  foundation  to
establish  the new  venture's  market  position in the growing  merchant  energy
trading business.  It is anticipated that CalBear trading  operations will begin
in the fourth quarter of 2005, following the requisite regulatory  approvals.  A
conference  call will take place today at 10:30 a.m.  eastern  daylight  savings
time to discuss this new venture.

     Commenting  on the  transaction,  Warren  Spector,  President  and Co-Chief
Operating  Officer  of Bear  Stearns,  said,  "We are  very  excited  about  the
formation of CalBear and working with Calpine in this venture.  This transaction
provides us with a unique  opportunity to quickly  become a leading  provider of
liquidity, execution and clearing services in the physical energy market without
compromising our disciplined  approach to risk and capital  allocation.  Many of
our hedge fund,  institutional  investor,  public  finance  and  private  equity
clients are active users of energy price risk management services. Acquiring the
expertise  necessary to properly serve their needs has been a strategic priority
for the  firm.  Calpine  was  our  choice  in  this  venture  because  of  their
professionalism and commitment to providing the best service to their clients."

     Peter Cartwright,  Calpine Chairman, President and Chief Executive Officer,
said,  "We are very  pleased  about the  creation of CalBear and teaming up with
Bear Stearns as we will build upon the  strengths of both of our  organizations.
This  energy  trading  venture  will  enable  us to  create  more  value for our
shareholders  and to provide  additional  opportunities  for our  customers  and
employees. As we looked to set up the ideal energy trading organization, we felt
strongly that venturing with the right  financial  institution was essential for
us to maximize  returns from  Calpine's  investments.  Bear Stearns is the right
institution."

     In  connection  with this  transaction,  Calpine has formed a wholly  owned
subsidiary,  Calpine Merchant Services Company,  Inc. (CMSC),  that will include
the employees and  information  infrastructure  of the highly  regarded  Calpine
subsidiary,  Calpine Energy  Services,  L.P. (CES).  CalBear has entered into an
agreement with CMSC that provides for CMSC to be its exclusive  agent to execute
power and natural gas trades with CalBear  clients that have entered into master
trading agreements guaranteed by Bear Stearns. CMSC will also provide scheduling
and back office  services to CalBear  from its offices in Houston.  CMSC will be
compensated  for its  services  through a service fee equal to 50 percent of the
profits of CalBear.

     The  transaction  also  includes  a  $350  million  credit   intermediation
agreement between CalBear and CES. Under the terms of this arrangement,  CalBear
will enter into approved  transactions  to sell power and acquire natural gas up
to 61 days in  advance  with  clients  that have  entered  into  master  trading
agreements  guaranteed by Bear Stearns. The economics of these transactions will
be passed on to CES through offsetting trades.  CalBear's  counterparty exposure
to CES will be  mitigated  through the use of margin  requirements  and a master
netting agreement covering all CES transactions with CalBear.  It is anticipated
that this credit  intermediation  agreement  will  provide  CES with  additional
flexibility  and the  opportunity  to expand the operating  margins of Calpine's
generating assets. In addition,  the agreement is expected to increase Calpine's
working  capital  position  through  the  return  of cash  currently  posted  as
collateral.

     In addition,  CMSC,  acting as agent for CES, will provide all of the asset
management  services required by Calpine's power generation fleet.  Calpine will
retain all of the economics of these assets.

Conference Call Information

     Bear  Stearns  and  Calpine  will host a  conference  call this  morning to
discuss  this energy  marketing  and trading  venture.  The call is scheduled to
begin at 10:30 a.m. eastern daylight savings time today, Thursday,  September 8,
2005. To participate via the teleconference  (in listen-only mode),  please dial
1-888-603-6685  (1-706-634-1265 for international callers) at least five minutes
before the start of the call. In addition, Calpine will simulcast the conference
call and presentation  live via the Internet.  The webcast and presentation will
be  available   for  30  days  on   Calpine's   investor   relations'   page  at
www.calpine.com.

About Bear Stearns

     Founded in 1923, Bear,  Stearns & Co. Inc. is a leading  investment banking
and  securities  trading  and U.S.  registered  brokerage  firm,  and the  major
subsidiary of The Bear Stearns  Companies Inc.  [NYSE:BSC].  With  approximately
$49.4 billion in total capital,  Bear Stearns serves governments,  corporations,
institutions  and  individuals   worldwide.   The  company's  business  includes
corporate finance and mergers and acquisitions, institutional equities and fixed
income  sales  and  trading,   securities  research,  private  client  services,
derivatives,  foreign  exchange and futures sales and trading,  asset management
and custody  services.  Through Bear,  Stearns  Securities  Corp.  (BSSC),  Bear
Stearns offers financing,  securities lending, clearing and technology solutions
to hedge funds,  broker-dealers and investment advisors. BSSC is a member of the
NYSE,  NASD  and  SIPC.   Headquartered  in  New  York  City,  the  company  has
approximately 11,000 employees worldwide.  For additional information about Bear
Stearns, please visit the firm's website at http://www.bearstearns.com.

About Calpine Corporation

     A  major  power  company,   Calpine  Corporation   supplies  customers  and
communities  with  electricity  from clean,  efficient,  natural  gas-fired  and
geothermal power plants. Calpine owns, leases and operates integrated systems of
plants in 21 U.S. states and three Canadian  provinces.  Its customized products
and services include wholesale and retail electricity,  natural gas, gas turbine
components  and  services,  energy  management,  and a wide range of power plant
engineering,  construction and operations services. Calpine was founded in 1984.
It is included in the S&P 500 Index and is publicly traded on the New York Stock
Exchange under the symbol CPN. For more information about Calpine,  please visit
the company's website at www.calpine.com.



Media Contact:       Russell Sherman                   Katherine Potter
                     Bear, Stearns & Co. Inc.          Calpine Corporation
                     (212) 272-5219                    (408) 995-5115, Ext. 1168

                                                       Meg Laidlaw
                                                       Calpine Corporation
                                                       (713) 830-8655

Investor Contact:    Elizabeth Ventura                 Rick Barraza
                     Bear, Stearns & Co. Inc.          Calpine Corporation
                     (212) 272-9251                    (408) 995-5115, Ext. 1125

                                                       Karen Bunton
                                                       Calpine Corporation
                                                       (408) 995-5115, Ext. 1121