The private mortgage insurance industry is expressing optimism with the positive changes seen lately in the housing market while hoping that Congress or the Obama administration do nothing to impede or spoil the market’s recovery. Industry executives say stabilizing home values, low interest rates, better quality mortgages and a shrinking FHA share of the mortgage market are helping MIs win back market share and write new business. “Everybody is trying to write as much business as they can to regain share,” said Michael Zimmerman, senior vice president for investor relations at Mortgage Guarany Insurance Corp. New insurance written is...