Even though big-box centers across the U.S. still are struggling with vacancies lingering from the liquidation of retailers such as Borders, Circuit City and Linens N' Things, the industry's average vacancy rate has declined in recent years.
The index is set to replace the Dow average on April 8 as the index whose action will be monitored for the sharp swings that trigger "circuit breakers" halting all U.S. stock trading.