The S&P 500 is again strugglingto poke into positive territory forthe year, after piling up a 3-year losingstreak. Does that streak meanthe market will rebound? Not necessarily,say Wall Street's number-crunchers,but a continuing declineis against the historical odds. Thelast time stocks hit the skids 4 yearsin a row was after the 1929 Crash,when economic conditions were farworse than they are today. Of the 57complete market years since theend of World War II, stocks havelost ground in only 17 and continuedto sink in only 3 of the yearsthat followed a losing year. Two ofthose 3 years were 2001 and 2002.: Stay the course withstocks or stock mutual funds.