Merrill Lynch Trust Company ranked as the most profitable bank or thrift with at least half of its assets in mortgages and mortgage securities as of the half-way point in 2005, according to a new Inside Mortgage Profitability analysis of call report data. The savings bank posted an 8.71 percent return on assets on a year-to-date basis, although most of its income came from trust activities, rather than its $123.8 million portfolio of MBS. … [One data table included]