LOS ANGELES — DCT Industrial Trust has agreed to purchase a four-property portfolio totaling 563,000 square feet for an undisclosed sum. The portfolio contains three properties within the Los Angeles International Airport submarket and one property within the Chicago O’Hare International Airport submarket. The Class A air freight buildings boast a 99.6 percent total occupancy rate. They are leased to eight tenants. The off-market transaction is anticipated to close in the fourth quarter of 2012.