UNAUDITED PRO FORMA CONSOLIDATED CONDENSED FINANCIAL INFORMATION
          KEYSPAN ENERGY CORP\LILCO COMBINATION AND LIPA TRANSACTION


The following unaudited pro forma financial  information reflects adjustments to
the historical  financial  statements of LILCO to give effect to the transfer of
LILCO's gas and generation  business to subsidiaries  of MarketSpan  Corporation
(MarketSpan),  the stock  acquisition  of LILCO by a wholly owned  subsidiary of
LIPA and the combination between KeySpan Energy Corporation  (KeySpan) and LILCO
(Combination).  The unaudited pro forma consolidated  condensed balance sheet at
March 31, 1998 gives effect to the LIPA  Transaction  and the  Combination as if
they had  occurred  at March 31,  1998.  The  unaudited  pro forma  consolidated
condensed statement of income for the 12-month period ended March 31, 1998 gives
effect to the LIPA  Transaction  and the  Combination as if they had occurred on
April 1, 1997.  These statements are prepared on the basis of accounting for the
Combination  under  the  purchase  method  of  accounting  and are  based on the
assumptions set forth in the notes thereto.

The following pro forma financial information has been prepared from, and should
be read in  conjunction  with,  the LIPA  Agreement  (Annex D to the Joint Proxy
dated June 27, 1997), and the historical  consolidated  financial statements and
related notes thereto of KeySpan and LILCO.  The  following  information  is not
necessarily indicative of the financial position or operating results that would
have occurred had the LIPA  Transaction and the Combination  been consummated on
the date, or at the beginning of the period,  for which the LIPA Transaction and
the  Combination  are being given  effect nor is it  necessarily  indicative  of
future operating results or financial position.




                             MARKETSPAN CORPORATION
            UNAUDITED PRO FORMA CONSOLIDATED CONDENSED BALANCE SHEET
                                       3/31/98
                                  (In Millions)


                                                          Sale                 MarketSpan 
                                           LILCO           to       Pro Forma   before     Keyspan       Pro Forma      
                                         (Historical)    LIPA (1)  Adjustments  KeySpan   (Historical)   Adjustments     MarketSpan
                                         -----------   ----------- ----------- ---------  ------------   -----------     ----------
                                                                                                         
ASSETS                                                                   
PROPERTY
Utility Plant
   Electric                                $4,031.6        2,929.4               1,102.2                                    1,102.2
   Gas                                      1,233.3            0.0               1,233.3       1,873.1                      3,106.4
   Common                                     290.2            0.0                 290.2                                      290.2
   Construction work in progress              118.7           41.1                  77.6                                       77.6
   Nuclear fuel in process and in reactor      18.1           18.1                   0.0                                        0.0
   Less - Accumulated depreciation              0.0            0.0                   0.0                                        0.0
       and amortization                    (1,877.8)        (952.3)               (925.5)       (474.8)                    (1,400.3)
                                         ----------- --------------   --------     ------- -------------  -------------    ---------
Total Net Utility Plant                     3,814.1        2,036.3       0.0     1,777.8       1,398.3            0.0       3,176.1
  Gas exploration and production, at cost       0.0            0.0                               723.6                        723.6
     Less - Accumulated depletion               0.0            0.0                              (256.5)                      (256.5)
                                                                                            -------------                 ----------
                                         ----------- -------------- ---------     -------                -------------
Total Net Plant                             3,814.1        2,036.3       0.0     1,777.8       1,865.4            0.0       3,643.2
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
                                         ----------- -------------- ---------                            -------------
Cost In Excess of Net Assets Acquired           0.0            0.0       0.0         0.0           0.0          177.0(6)      177.0
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
REGULATORY ASSETS
Base financial component  (less accumulated
   amortization of $883.5 )                 3,155.3        3,155.3
Rate moderation component                     434.0          434.0
Shoreham post-settlement costs              1,005.3        1,005.3
Regulatory tax asset                        1,737.9        1,716.9                  21.0                         67.7  (5)     88.7
Postretirement benefits other than pensions   340.1            0.0    (287.7)(2)    52.4                          0.0          52.4
Other                                         419.2          329.2                  90.0                         29.4  (6)    119.4
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
Total Regulatory Assets                     7,091.8        6,640.7    (287.7)      163.4           0.0           97.1         260.5
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
NONUTILITY PROPERTY AND OTHER INVESTMENTS      50.8           17.9       0.0        32.9         105.5          (64.8)(16)     73.6
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
CURRENT ASSETS
Cash and cash equivalents                     180.9           75.0   2,482.5 (3) 2,418.4          72.1                      2,555.3
                                                                        75.0(10)
                                                                        (4.6)(11)
                                                                       (21.0)(12)
                                                                        64.5(12)
                                                                       (33.9)(12)
                                                                      (250.0)(13)                                 64.8 (16)
Deferred tax asset                              0.0            0.0     236.6 (4)   236.6           0.0                        236.6
Accounts receivable and accrued revenues      466.1          328.6      14.4 (2)   151.9         335.3                        487.2
Other Current Assets                          211.3            3.3     (64.5)(12)  143.5          76.8                        220.3
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
TOTAL CURRENT ASSETS                          858.3          406.9   2,499.0     2,950.4         484.2           64.8       3,499.4
DEFERRED CHARGES                               85.7           47.7       0.0        38.0         180.4         (104.4)(5)(6)  114.0
                                         ----------- -------------- ---------     ------- -------------  -------------     ---------
CONTRACTUAL RECIEVABLE FROM LIPA                0.0            0.0     273.3 (2)   273.3           0.0            0.0         273.3
                                         ----------- -------------- ---------     ------- -------------  -------------     ---------
TOTAL ASSETS                               11,900.7        9,149.5   2,484.6     5,235.8       2,635.5          169.7       8,041.0
                                         =========== ============== =========     ======= =============  =============    ==========


CAPITALIZATION AND LIABILITIES
CAPITALIZATION
Common Shareowners' Equity                  2,662.5        2,500.8   2,497.5 (3) 2,605.6       1,083.5          136.4  (6)  3,812.5
                                                                       (15.0)(3)                                (13.0) (6)
                                                                       (13.0)(6)
                                                                       (21.0)(12)
                                                                        (4.6)(11)
                                                                                                                 (6.4)(17)     (6.4)
Long-term debt, includes 
  current maturities                        4,482.9        3,396.1               1,086.8         782.1            6.4 (17)  1,875.3
Preferred stock                               702.0          339.0                 438.0           0.0            0.0         438.0
                                                                        75.0(10)                                                0.0
                                         ----------- --------------   ---------     ------- -------------  -------------  ----------
Total Capitalization                        7,847.4        6,235.9   2,518.9     4,130.4       1,865.6          143.4       6,119.4
                                         ----------- -------------- ---------     ---------------------  -------------    ----------
REGULATORY LIABILITIES                        389.4          365.1       0.0        24.3           0.0            0.0          24.3
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
CURRENT LIABILITIES
Accounts payable and accrued expenses         228.6          101.7      13.0 (6)   139.9         110.0           46.3(6)      296.2

Accrued taxes (including 
  Federal income tax)                          34.8                    399.0 (4)   346.3          38.4                        384.7
                                                                       (87.5)(13)
Other current liabilites                      324.0           52.7                 271.3         115.7            0.0         387.0
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
                                              587.4          154.4     324.5       757.5         264.1           46.3       1,067.9
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
DEFERRED CREDITS
Deferred federal income tax                 2,539.4        2,377.0    (162.4)(4)    87.5         288.9                        376.4
                                                                        87.5(13)
Other                                          69.4           19.7                  49.7         119.9                        169.6
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
Total Deferred Credits                      2,608.8        2,396.7     (74.9)      137.2         408.8            0.0         546.0
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
OPERATING RESERVES                            467.7           (2.6)    (33.9(12)   436.4           0.0            0.0         436.4
                                                                      (250.0(13)  (250.0)                                    (250.0)
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
COMMITMENTS AND CONTINGENCIES                   0.0            0.0       0.0         0.0           0.0            0.0           0.0
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
MINORITY INTEREST IN SUBSIDIARY COMPANY         0.0            0.0       0.0         0.0          97.0            0.0          97.0
                                         ----------- -------------- ---------     ------- -------------  -------------    ----------
TOTAL CAPITALIZATION AND LIABILITIES       11,900.7        9,149.5   2,484.6     5,235.8       2,635.5          169.7       8,041.0
                                         =========== ============== =========    ======= =============  =============    ==========


SEE ACCOMPANYING NOTES TO UNAUDITED PRO FORMA CONSOLIDATED  CONDENSED  FINANCIAL
STATEMENTS.


                             MARKETSPAN CORPORATION
         UNAUDITED PRO FORMA CONSOLIDATED CONDENSED STATEMENT OF INCOME
                   FOR THE TWELVE MONTHS ENDED MARCH 31, 1998
                     (In Millions Except Per Share Amounts)


 
                                                        Sale          Pro        MarketSpan
                                             LILCO        to          Forma         before     KeySpan      Pro Forma
                                         (Historical)  LIPA (1)     Adjustments    KeySpan    (Historical)  Adjustments  MarketSpan
                                         -----------  -----------   ----------   -----------  -----------   -----------  -----------
                                          

REVENUES
                                                                                                          
Electric                                   $2,478.4     $2,100.6      $11.5(7)       $389.3         $0.0                     $389.3
Gas - Utility sales                           645.7                                   645.7      1,299.5                    1,945.2
Gas production and other                                                                0.0        130.5                      130.5
                                          --------  -----------   --------     -----------  -----------     -----------  -----------
Total Revenues                              3,124.1      2,100.6       11.5         1,035.0      1,430.0             0.0    2,465.0

OPERATING EXPENSES
Operations - fuel and purchased power         957.8        658.3                      299.5        524.7                      824.2
Operations - other                            400.0        244.8                      155.2        365.5                      520.7
Maintenance                                   111.1         62.3                       48.8         57.1                      105.9
Depreciation, depletion and amortization      158.5         95.4                       63.1        128.5            2.9(6)    194.5
Base financial component amortization         101.0        101.0                        0.0          0.0                        0.0
Rate moderation component amortization        (35.1)       (35.1)                       0.0          0.0                        0.0
Regulatory liability component amortizatio    (88.6)       (88.6)                       0.0          0.0                        0.0
Other regulatory amortization                  47.3         36.0                       11.3          0.0                       11.3
Operating taxes                               466.3        261.6                      204.7        150.0                      354.7
Federal income taxes                          237.5        205.5        4.0(8)         36.0         58.3                       94.3
                                          --------  -----------    ----------     -----------  -----------     ----------- ---------
Total Operating Expenses                    2,355.8      1,541.2        4.0           818.6      1,284.1             2.9    2,105.6
                                          --------  -----------    ----------     -----------  -----------     ----------- ---------
Operating Income                              768.3        559.4        7.5           216.4        145.9            (2.9)     359.4

Other Income and (Deductions)                  (1.6)        29.5                      (31.1)        25.1                       (6.0)
                                          --------  -----------    ----------     -----------  -----------     -----------  --------
Income Before Interest Charges                766.7        588.9        7.5           185.3        171.0            (2.9)     353.4

Interest Charges                              404.5        311.6                       92.9         44.5                      137.4
                                          --------  -----------    ----------     -----------  -----------     ----------- ---------
NET INCOME                                    362.2        277.3        7.5            92.4        126.5            (2.9)     216.0
                                          --------  -----------    ----------     -----------  -----------     -----------   -------
Preferred stock dividend requirements          51.8         22.9        6.0(10)        34.9          0.1                       35.0
                                          --------  -----------    ----------     -----------  -----------     ----------- ---------
EARNINGS FOR COMMON STOCK                    $310.4       $254.4       $1.5           $57.5       $126.(14)        ($2.9)    $181.0
                                          ========  ===========    ==========     ===========  ===========     =========== =========

Average Common Shares Outstanding             121.4        121.4      121.4           121.4         50.7           (14.7)     157.4
                                          ========  ===========    ==========     ===========  ===========     ===========  ========

EARNINGS PER COMMON AND EQUIVALENT SHARES     $2.56       $2.10       $0.01           $0.47        $2.49                    $1.15(9)
                                          ========  ===========    ==========     ===========  ===========                 =========



SEE ACCOMPANYING NOTES TO UNAUDITED PRO FORMA CONSOLIDATED  CONDENSED  FINANCIAL
STATEMENTS.



NOTES TO UNAUDITED PRO FORMA CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

1. The  historical  financial  statements  of LILCO have been  adjusted  to give
effect to the  transaction  with LIPA on May 28,  1998,  pursuant to which LILCO
transferred  certain  of its net  assets  relating  to its  gas  and  generation
business ("Transferred Assets") to subsidiaries of MarketSpan Corporation.  LIPA
then  acquired  LILCO  in a  stock  sale.  The  adjustments  are  based  upon  a
disaggregation  of LILCO's  balance  sheet and  operations  as  estimated by the
management of MarketSpan, and are subject to adjustment pursuant to the terms of
the LIPA agreement.

     In connection with this transaction,  the principal assets acquired by LIPA
through its stock  acquisition  of LILCO include the electric  transmission  and
distribution system ("The LIPA Transmission and Distribution  System"),  LILCO's
18%  interest  in Nine Mile Point 2 nuclear  power  station,  certain of LILCO's
regulatory  assets  associated  with its electric  business and an allocation of
accounts receivable and other assets. The principal  liabilities assumed by LIPA
include LILCO's regulatory  liabilities associated with its electric business, a
portion of LILCO's long-term debt and an allocation of accounts payable, accrued
expenses, customer deposits, other deferred credits and claims.

2. In connection with the LIPA  Transaction,  LIPA is contractually  responsible
for reimbursing MarketSpan for postretirement benefits other than pension costs,
related to employees of LILCO's  electric  business.  A pro forma adjustment has
been reflected to reclassify the associated  regulatory asset for postretirement
benefits  other than  pensions to current and  non-current  accounts  receivable
pursuant to LIPA's obligation to a subsidiary of MarketSpan.

3. The Cash Purchase Price paid by LIPA in connection with its stock acquisition
of LILCO was $2,497.5  million as  determined  based upon the estimated net book
value of the LILCO Retained Assets of $2,500.8  million.  In addition,  the LIPA
Transaction  required MarketSpan upon the closing of the transaction to remit to
LIPA $15  million  associated  with  the  certain  real  estate  tax  litigation
recoveries. The net cash received by MarketSpan amounted to:

       Cash Purchase Price                      $2,497.5
       Cash paid to LIPA                           (15.0)
                                                --------
       Net Cash                                 $2,482.5
                                                ========

4. The  Transferred  Assets from LILCO to subsidiaries of MarketSpan will result
in the  imposition  of federal  income  taxes on LILCO.  Pursuant  to the Merger
Agreement,  the  subsidiaries  created by MarketSpan will receive the benefit of
the  increased  tax  basis  of the  Transferred  Assets  and  will  receive  the
Transferred  Assets net of the tax imposed on LILCO. The tax is derived from the
difference  between the fair market  value of the  Transferred  Assets and their
existing tax basis.  There are many  different  ways of valuing assets which may
result in substantially  different values.  MarketSpan has retained professional
appraisers to assist it in determining  the fair market value of the Transferred
Assets.  However,  the valuation  determined by its appraisers is not binding on
the  Internal  Revenue   Service,   which  may  assert  a  higher  value  and  a
correspondingly  greater tax  liability.  Thus, the actual tax liability and the
amount of cash that will be available to MarketSpan net of such liability cannot
be determined at this time. The unaudited pro forma  consolidated  balance sheet
as of March 31, 1998,  reflects an estimated tax liability of approximately $399
million based upon an estimate of the value of the Transferred  Assets.  For pro
forma  financial  reporting  purposes,  the  subsidiaries  reversed the existing
deferred tax liability of $162 million  relating to the  Transferred  Assets and
recorded a $237 deferred tax asset,  reflecting the estimated  income tax effect
by which the tax basis of the Transferred Assets exceeded their book basis.

5. The unaudited pro forma condensed  consolidated balance sheet as of March 31,
1998 reflects the  reclassification  of $67.7 million of KeySpan  regulatory tax
assets  from  deferred  charges to  regulatory  assets in order to  consistently
present the regulatory assets.


6. The  purchase  price for  KeySpan,  which  amounted to  approximately  $1.260
billion including certain  transaction costs not recoverable  through rates, has
been  determined  based upon an average of LILCO's  opening  and  closing  stock
prices for the two trading days before and three trading days after December 29,
1996,  the  Transaction  date.  The purchase  price has been allocated to assets
acquired and liabilities  assumed based upon their estimated fair values.  It is
anticipated that the fair value of the utility assets acquired is represented by
their book value, which approximates the value of these assets recognized by the
New York State Public Service  Commission (PSC) in establishing  rates which are
designed to, among other things, provide for a return on the book value of these
assets and the  recovery of costs  included  as  depreciation  and  amortization
charges.  The estimated fair values of KeySpan  non-utility  assets  approximate
their carrying values.


At March 31, 1998,  the purchase price exceeded the fair value of the net assets
acquired by $177.0 million,  which MarketSpan expects to amortize over 40 years.
The actual  amount of goodwill  to be  recorded  will be based on the net assets
acquired as of the closing date.


MarketSpan  estimates total transaction costs related to the KeySpan Transaction
to be $70 million,  $23.7 million of which has been  incurred  through March 31,
1998. Accordingly,  a pro forma adjustment of $46.3 million has been recorded to
reflect  additional  transaction costs anticipated to be incurred  subsequent to
March  31,  1998.  Of the  total  transaction  costs,  $29.4  million  has  been
reclassified  to  Regulatory  Assets as  MarketSpan  will recover  these amounts
through rates charged to its gas customers.

In  addition,  MarketSpan  estimates  transaction  costs  related  to  the  LIPA
Transaction  to be $26 million,  $13 million of which has been incurred  through
March 31,  1998.  A pro forma  adjustment  of $13 million  has been  recorded to
reflect the additional costs anticipated to be incurred  subsequent to March 31,
1998.

7. The agreement  with LIPA  includes a provision for  MarketSpan to earn in the
aggregate  approximately  $11.5 million in annual  management  service fees from
LIPA for the management of the LIPA Transmission and Distribution System and the
management  of all  aspects  of fuel and power  supply.  These  agreements  also
contain certain  incentive and penalty  provisions which could materially impact
earnings from such agreements.


8. The net pro forma  charge of $4.0  million  represents  the income tax effect
associated with the recording of the pro forma adjustments for the $11.5 million
management fee (See Note 7).


9. No adjustments have been made to earnings on common stock to reflect earnings
on net available  proceeds of approximately  $1.6 billion to be received,  after
remittances  to  subsidiaries  of MarketSpan of  approximately  $350 million for
working  capital  purposes,  (see  Note  3)  payment  of  taxes  related  to the
Transferred  Assets and the funding of VEBA Trusts (see Note 13). If these funds
were  invested at 5.93% (the 30 year US Treasury  Bond yield at March 31, 1998),
MarketSpan  would have realized  additional  interest  income,  net of taxes, of
approximately  $60.6 million,  or  approximately  $.39 per share, on a pro forma
consolidated  basis. Each one percent change in the assumed interest rate, would
increase/decrease  interest  income,  net of taxes,  by $11.0  million.  LILCO's
allowed rate of return on its common  equity for its  electric  business for the
year ended March 31, 1998 was 11%.

10.   As   more   fully   described   in  the   section   entitled   "The   LIPA
Transaction-Agreement  and Plan of  Merger,"  as  described  in the Joint  Proxy
Statement/Prospectus  dated June 27, 1997,  LILCO  transferred  the  Transferred
Assets to subsidiaries of MarketSpan in exchange for shares of MarketSpan common
stock,  and $75 million face amount of  privately  placed  MarketSpan  Preferred
Stock.   This  Preferred  Stock,   issued  in  two  series,  is  non-voting  and
non-convertible.  One series has a term of seven years and the other series h as
a term of ten  years.  For  purposes  of these pro forma  financial  statements,
MarketSpan has issued $75 million of Preferred Stock which LILCO re-sold for $75
million  and  retained  the  proceeds  (i.e.  a  Retained  Asset).  A pro  forma
adjustment of $5.3 million has been recorded to reflect the increased  preferred
stock dividend requirements.

11. A pro forma  adjustment  in the amount of $4.6  million  was made to reflect
call premiums,  related to the  redemption of certain series of LILCO  preferred
stock.

12. A pro  forma  adjustment  of $21.0  million  has been  recorded  to  reflect
benefits  payable to LILCO officers  subsequent to March 31, 1998 resulting from
the completion of the LIPA and KeySpan  Transactions.  These amounts principally
relate to incentive  compensation  plans,  transaction  related  incentives  and
contract benefits. In accordance with previously executed employment agreements,
LILCO  paid  during  the  fiscal  year  ended  March 31,  1998 and  through  the
Transaction  date a total of $67  million  to its  officers.  Approximately  $42
million  of  such  payments  related  to its  chairman  and $25  million  to its
officers.

13. A pro forma adjustment of $250 million to reflect the funding of VEBA trusts
related to LILCO's  obligations  with respect to post employment  benefits other
than pensions with proceeds from the LIPA  Transaction  and the  associated  tax
benefits of $87.5 million.

14.  KeySpan  earnings  for the 12 month  period  ended March 31, 1998  included
non-recurring net gains of $0.25 per share.

15. The unaudited pro forma consolidated  condensed financial statements reflect
the exchange of each share of LILCO Common Stock  outstanding  into 0.880 shares
of MarketSpan  common stock and each share of KeySpan  common stock  outstanding
into one share of  MarketSpan  common  stock,  as provided in the  KeySpan/LILCO
Agreement.

16. A pro forma adjustment has been recorded to reflect the repayment by LIPA of
amounts  funded  by LILCO  and  KeySpan  to  purchase  an  interest  rate  hedge
instrument. The repayment includes principal plus interest.

17. A pro  forma  adjustment  has been  recorded  to  reflect  the  issuance  of
MarketSpan  preferred  stock, the proceeds from which were used to fund employee
401(k) plans.