Is a Marin County real estate investment trust about to ride back into the valley of death of far more than 600? According to the Wall Street Journal, Mill Valley's Redwood Trust Inc. looks set to put "at least" $200 million of residential mortgage-backed securities on the market, as early as this week. This would be the first time since the market collapsed in 2007 that securities supported by privately backed, newly originated home loans see the light of day. Should Redwood Trust go ahead, said the Journal, "it could mark a small but important step toward healing a (devastated) market." I got a firm "no comment" when I checked in with the firm on Tuesday. But reading through its public materials, in particular its fourth quarter 2009 shareholder "review," its intentions seem clear. While Fannie Mae, Freddie Mac and the Federal Housing Administration now back more than 90 percent of newly originated home loans - a situation Redwood Trust calls "unsustainable" - the firm says it already sees "progress on restarting" the private market.