Ten years ago, there were more than 1,100 enclosed shopping malls in the U.S. Since then, more than 400 have been shuttered—become “ghost malls”—or have been repurposed for use other than retail space, such as for industrial, educational or office space, according to Yahoo Finance.

And although the trend may be slowing—commercial real estate tracker Reis reports the vacancy rate for regional malls declined to 7.9% in fourth-quarter 2013, down from 8.2% in the previous quarter, and strip mall vacancy declined to 10.4%, down from 10.5% in Q3—the de-mallification of America isn't likely to stop. About 15% of U.S. malls will fail or be converted into non-retail space within the next 10 years, predicts Green Street Advisors, a real estate and REIT analytics firm.

Vacant or underpopulated malls and other large, deserted commercial spaces are a unique challenge for insurance—especially agents and brokers who specialize in real estate coverage. We spoke with Evan Bull, national property practice leader at Burns & Wilcox Brokerage, where ghost malls are a niche market, about the unique trends and risks presented by vacant malls. Bull, who spent most of his career on the retail side, discussed ghost malls and other vacant space not as a blight but an opportunity for the industry.