Accelerating growth, inroads by REITs, and continuity among the industry leaders mark the first 10 years of the NMHC 50. Between 1990 and 1999, the number of apartments owned by the nation's 50 largest apartment owners grew from 1.66 million to 2.32 million, a gain of 40%.

Comparable growth was recorded in the NMHC 50 of apartment managers. The growth accelerated toward the end of the decade. The increase in total holdings from 1995 to 1999 was almost triplethe net gain between 1990 and 1995.

The growth has been most rapid at the very top of the NMHC 50. AIMCO, the largest owner in 1999, with 233,329 apartments, had an ownership interest in nearly three times as many apartments as the top firm in 1990, NHP Inc., with 81,418. At the same time, the entry threshold went up only about one-third from the 14,504 apartments owned by No. 50 in 1990, to 19,697 in 1999.

Real estate investment trusts account for much of the acceleration in growth during the past several years of the NMHC 50. No publicly traded REITs were in the NMHC 50 in 1990 (although several of the 1990 firms subsequently elected REIT status). In 1999, there are 17 REITs in the ownership rankings, including the giants in the No. 1 and No. 2 positions, and REITs account for 42% of the aggregate apartment holdings of the entire NMHC 50.

Yet, despite these significant changes, continuity has also been a hallmark of the 10 years of the NMHC 50. No fewer than 18 companies have been on the ownership list in all 10 years, and 11 companies have been on the management list in all 10 years. Among these stalwarts, the Related Cos. and Lincoln Property Co. deserve special recognition for being near the top of the rankings each of the 10 years.