President George W. Bush has signed a massive housing bill intended to provide mortgage relief for 400,000 struggling U.S. homeowners and stabilize financial markets. A White House spokesman said Bush signed the measure Wednesday to «improve confidence and stability in markets and to provide better oversight of Fannie Mae and Freddie Mac. » The measure offers a temporary financial lifeline to troubled mortgage companies Fannie Mae and Freddie Mac and tightens controls over the two government-sponsored businesses. It is regarded as the most significant U.S. housing legislation in decades. It lets homeowners who cannot afford their payments refinance into more affordable government-backed loans rather than losing their homes, the Associated Press reported.