April 29 (Reuters) -
* FITCH: HOUSING DOWNTURN COULD PRESSURE AUSTRALIAN BANK RATINGS
* FITCH- MORTGAGE PORTFOLIOS OF AUSTRALIA'S 4 MAJOR BANKS COULD WITHSTAND HOUSING MARKET DOWNTURN WITHOUT EXPERIENCING LOSSES THAT THREATEN VIABILITY
* FITCH ON AUSTRALIAN BANKS-RATINGS WOULD BE LIKELY TO COME UNDER PRESSURE IN SEVERE SCENARIOS WHERE BANKS SUFFER FROM LARGE SECOND-ORDER ECONOMIC EFFECTS