Shopping malls across the U.S. continue to lose value at a dramatic pace, and there is no indication that they are approaching a bottom.

Malls were the only property type to lose value in Green Street Advisors' Commercial Property Price Index report for January, losing 5% in a month when no other asset class saw movement. The drop was enough for malls to bring the entire CPPI down by 0.5%.

The longer the time frame, the steeper the decline in mall value looks. For the 12-month period ending in January, malls lost 15% of their value in Green Street's index, which places emphasis on the better-performing properties of each asset class it tracks. That could be doubly concerning for mall owners, considering the popular opinion over the past few years has been that Class-B and C malls have been hit much harder by changes to the industry than elite malls.

"A secular shift away from department stores and other mall retailers has caused many investors to red-line the space, and best-guess estimates put prices as much as 30% below the levels of three years ago,” Green Street Managing Director Peter Rothemund said in a statement released with the CPPI report.

In general, the retail brands that have been most likely to either go bankrupt or close wide swathes of stores in the past few years have been closely associated with malls, whether department stores like Sears and Macy's or in-line apparel retailers like Payless ShoeSource. Last year, over 9,300 stores went vacant, an all-time record that may not stand for long.

By mid-January, 1,700 planned closures had already been announced this year. While Simon Property Group and Brookfield Property Partners have bought Forever 21 out of bankruptcy to keep its considerable footprint operational, Macy's added 125 anticipated store closures to the 2020 count in the first week of February.

For mall owners with enough capital, the popular response to losing anchor tenants has been to redevelop the boxes into alternate uses. If malls continue to lose value and scare away investors, those internal capital requirements will increase, possibly leading to more consolidation in the sector.