The profitability of mortgage banking operations across the industry clearly began to ebb during the last three months of 2003, according to updated earnings releases analyzed by Inside Mortgage Profitability. The 24 companies that have reported fourth-quarter earnings so far turned in a combined $3.95 billion in mortgage banking profits for the period. That was down 15 percent from the $4.63 billion these same two dozen lenders reported during the previous quarter.