BOSTON-As a commercial real estate sector matures, conventional wisdom suggests it attracts increasing interest from larger investors, such as real estate investment trusts and institutions. These well-heeled buyers often have sizable investment allocation targets, and it's usually not practical for them to try to achieve those objectives with one-off deals. Thus, as a sector matures, the proportion of portfolio sales increases relative to single-asset sales.

Has that maturation been occurring in the healthcare real estate market, specifically among medical office buildings? Mindy Berman, a managing director with Jones Lang LaSalle and its Healthcare Solutions Group, suspected that it was. So she and her research team recently dug into 12 years of data to see if the theory was valid. Their conclusion? It sure looks that way.

For its analysis, JLL defined portfolio sales as transactions involving at least two properties selling for a total of $50 million or more. The data, drawn from Real Capital Analytics Inc. and JLL's research, revealed that portfolio sales totaled about $1.1 billion in 2007, accounting for slightly more than 21% of the total MOB sales volume of nearly $5 billion. But by 2012, portfolios accounted for a much greater share of MOB sales: more than 34 percent. That was slightly more than $2 billion in a record year in which MOB sales reached almost $6 billion.