The national economic downturn appears to be reversing the long-standing trend in which larger college endowments earn more than smaller endowments. Of course this year, the comparisons are about losses, not gains. The Wall Street Journal reported that in the fiscal year ending today, the five largest college and university endowments anticipate final losses in the 25-30 percent range. But examining data from Northern Trust Corp., which manages 90 endowments, the Journal found that the median loss for endowments for institutions with less than $100 million was only 16 percent.