<PAGE>
<PAGE>
SUPPLEMENT TO
PROSPECTUS SUPPLEMENT DATED MAY 25, 1999
(TO PROSPECTUS DATED MAY 25, 1999)
PNC MORTGAGE SECURITIES CORP.
DEPOSITOR AND MASTER SERVICER
MORTGAGE PASS-THROUGH CERTIFICATES, SERIES 1999-5
$1,071,055,419
(APPROXIMATE)
The Servicing Fees with respect to four of the Group II Loans and 109 of
the Group III Loans were incorrectly reflected and therefore certain related
Pass-Through Rates and certain other related calculations were incorrect in the
Prospectus Supplement dated May 25, 1999 to the Prospectus dated May 25, 1999.
Accordingly, such Prospectus Supplement is amended as follows:
<TABLE>
<S> <C>
S-5, S-31: The initial class notional amount for the Class II-X Certificates set forth as '$11,648,711' in the
second sentence of footnote (2) on page S-5 and in the last sentence of the fourth full paragraph on
page S-31 under the caption 'Description of the Certificates -- Distributions of Interest' is
amended to read '$11,731,677.'
S-5, S-31: The initial class notional amount for the Class III-X-2 Certificates set forth as '$6,785,467' in
the second sentence of footnote (2) on page S-5 and in the last sentence of the sixth full paragraph
on page S-31 under the caption 'Description of the Certificates -- Distributions of Interest' is
amended to read '$7,095,730.'
S-5, S-31: The initial class notional amount for the Class III-X-3 Certificates set forth as '$4,148,185' in
the second sentence of footnote (2) on page S-5 and in the last sentence of the seventh full
paragraph on page S-31 under the caption 'Description of the Certificates -- Distributions of
Interest' is amended to read '$4,811,498.'
S-53: The weighted average Servicing Fee for the Group II Loans set forth as approximately '0.738%' and
the highest Servicing Fee for the Group II Loans set forth as '1.600%,' in each case under the
caption 'Description of the Certificates -- Servicing Compensation and Payment of Expenses' on page
S-53, are amended to read '0.735%' and '1.470%,' respectively.
S-53: The weighted average Servicing Fee for the Group III Loans set forth as approximately '0.797%' and
the highest Servicing Fee for the Group III Loans set forth as '1.800%,' in each case under the
caption 'Description of the Certificates -- Servicing Compensation and Payment of Expenses' on page
S-53, are amended to read '0.772%' and '1.520%,' respectively.
S-60: In the table entitled 'Groups of Hypothetical Mortgage Loans -- Loan Group II' under the caption
'Yield and Prepayment Considerations -- Prepayment Assumptions' on page S-60, the percent indicated
thereunder in the second row of such table as the Pass-Through Rate is amended to read
'7.2801186307%.'
S-60: In the table entitled 'Groups of Hypothetical Mortgage Loans -- Loan Group III under the caption
'Yield and Prepayment Considerations -- Prepayment Assumptions' on page S-60, the percents indicated
thereunder in the third and fourth row of such table as the Pass-Through Rate are amended to read
'7.5561015060%' and '8.1073979777%,' respectively.
</TABLE>
<PAGE>
<PAGE>
<TABLE>
<S> <C>
S-83: The table indicating the Pass-Through Rates for the Group II Loans on page S-83 is amended and
restated in its entirety as follows:
</TABLE>
<TABLE>
<CAPTION>
PASS-THROUGH RATES OF THE GROUP II LOANS
- ----------------------------------------------------------------------------------------------------------------------------
AGGREGATE PRINCIPAL
BALANCE OF THE WEIGHTED AVERAGE
MORTGAGE LOANS WEIGHTED AVERAGE SCHEDULED
RANGE OF AS OF THE MORTGAGE REMAINING TERM
PASS-THROUGH RATES (%) CUT-OFF DATE INTEREST RATES (IN MONTHS)
- ----------------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C>
6.001 - 6.250%................................................ $ 505,716.44 6.440% 359
6.251 - 6.500%................................................ 765,000.00 6.750 360
6.501 - 6.750%................................................ 10,327,107.66 7.198 354
6.751 - 7.000%................................................ 46,335,342.71 7.587 358
7.001 - 7.250%................................................ 21,259,680.05 7.803 357
7.251 - 7.500%................................................ 31,314,990.24 8.315 351
7.501 - 7.750%................................................ 21,590,255.82 8.505 356
7.751 - 8.000%................................................ 15,050,229.00 8.495 353
8.001 - 8.250%................................................ 4,678,165.22 9.082 358
8.251 - 8.500%................................................ 1,033,322.35 9.067 359
8.501 - 8.750%................................................ 1,461,600.00 9.662 360
9.001 - 9.250%................................................ 794,648.31 10.000 359
------------------- ------ ---
$155,116,057.80 8.033%* 355*
-------------------
-------------------
</TABLE>
- ------------------------
* Represents a weighted average of all the Group II Loans.
As of the Cut-Off Date, the Pass-Through Rates for the Group II Loans
ranged from approximately 6.075% per annum to approximately 9.010% per annum,
with a weighted average of approximately 7.254% per annum.
<TABLE>
<S> <C>
S-85: The table indicating the Pass-Through Rates for the Group III Loans on page S-85 is amended and
restated in its entirety as follows:
</TABLE>
<TABLE>
<CAPTION>
PASS-THROUGH RATES OF THE GROUP III LOANS
- -------------------------------------------------------------------------------------------------------------------------------
AGGREGATE PRINCIPAL
BALANCE OF THE WEIGHTED AVERAGE WEIGHTED AVERAGE
MORTGAGE LOANS MORTGAGE SCHEDULED
RANGE OF AS OF THE INTEREST REMAINING TERM
PASS-THROUGH RATES (%) CUT-OFF DATE RATES (IN MONTHS)
- -------------------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C>
5.501 - 5.750%.............................................. $ 182,142.36 6.875% 352
5.751 - 6.000%.............................................. 112,234.58 7.000 352
6.001 - 6.250%.............................................. 750,549.48 6.500 357
6.251 - 6.500%.............................................. 1,226,967.11 6.717 359
6.501 - 6.750%.............................................. 6,660,354.07 6.954 357
6.751 - 7.000%.............................................. 52,540,696.83 7.529 358
7.001 - 7.250%.............................................. 69,529,416.97 7.898 358
7.251 - 7.500%.............................................. 50,216,145.56 8.430 358
7.501 - 7.750%.............................................. 56,015,097.88 8.510 358
7.751 - 8.000%.............................................. 21,577,037.11 8.790 357
8.001 - 8.250%.............................................. 8,466,207.95 9.185 356
8.251 - 8.500%.............................................. 3,689,599.11 9.347 358
8.501 - 8.750%.............................................. 1,915,659.32 9.643 355
8.751 - 9.000%.............................................. 976,354.06 9.839 332
9.001 - 9.250%.............................................. 625,219.18 10.125 353
9.251 - 9.500%.............................................. 335,170.89 10.328 346
9.501 - 9.750%.............................................. 338,858.21 10.527 311
9.751 - 10.000%.............................................. 29,308.23 10.750 232
10.001 - 10.250%.............................................. 183,558.06 11.023 319
10.251 - 10.500%.............................................. 48,530.46 11.375 292
10.751 - 11.000%.............................................. 35,830.47 11.875 296
11.001 - 11.250%.............................................. 38,516.60 12.000 296
11.251 - 11.500%.............................................. 35,937.90 12.250 295
--
------------------- -----
$268,529,392.09 8.187%* 358*
-------------------
-------------------
</TABLE>
- ------------------------
* Represents a weighted average of all the Group III Loans.
As of the Cut-Off Date, the Pass-Through Rates for the Group III Loans
ranged from approximately 5.725% per annum to approximately 11.260% per annum,
with a weighted average of approximately 7.369% per annum.
The date of this Supplement is June 18, 1999.
2
