<PAGE>
SUPPLEMENT
(TO PROSPECTUS DATED FEBRUARY 18, 1997 AND PROSPECTUS SUPPLEMENT DATED
FEBRUARY 20, 1997)
$198,507,953 [NORWEST
LOGO]
(APPROXIMATE)
NORWEST ASSET SECURITIES CORPORATION ("NASCOR")
SELLER
MORTGAGE PASS-THROUGH CERTIFICATES, SERIES 1997-3
PRINCIPAL AND INTEREST PAYABLE MONTHLY, COMMENCING IN MARCH 1997
---------------
The table on page S-72 of the Prospectus Supplement is hereby replaced in
its entirety with the following:
<TABLE>
<CAPTION>
LIQUIDATION
YEAR OF FREQUENCY LOSS SEVERITY
ORIGINATION PERCENTAGE(A) PERCENTAGE(B)
- ----------- ------------- -------------
<S> <C> <C>
1987................................................ 1.10% 31.97%
1988................................................ 0.71% 32.26%
1989................................................ 1.46% 30.18%
1990................................................ 0.66% 25.28%
1991................................................ 0.26% 23.34%
1992................................................ 0.14% 16.04%
1993................................................ 0.07% 18.16%
1994................................................ 0.06% 0.42%
1995................................................ 0.03% 4.38%
1996................................................ 0.00% 0.00%
</TABLE>
- -------
(a) The liquidation frequency percentage is determined by dividing the
original principal balance of liquidated 30 Year RELO Mortgage Loans
originated during such year by the original principal balance of 30 Year
RELO Mortgage Loans originated during such year.
(b) The loss severity percentage is determined by dividing the amount of
losses resulting from liquidated 30 Year RELO Mortgage Loans originated
during such year by the original principal balance of liquidated 30 Year
RELO Mortgage Loans originated during such year.
---------------
BEAR, STEARNS & CO. INC.
APRIL 1, 1997
