Hedge funds are betting more and more money against brick-and-mortar retailers.

Average short interest, or bets that shares will fall, for members of the S&P 1500 retailing group now stands at 13 percent of float, according to a report last week from Bespoke Investment Group. That’s the highest level since December 2008.

Source: Bespoke Investment Group

“Not since the depths of the financial crisis have traders been more negative on the group,” the Bespoke report said.

Traditional brick-and-mortar retailers have struggled to compete against Amazon and other online sellers that frequently offer lower prices and greater convenience for consumers shopping from home. But that trend has seemed to accelerate this year, and hedge funds are taking notice.

In the first quarter of this year, nine retailers filed for Chapter 11 bankruptcy protection, matching the number of filings for all of 2016 and tracking for the highest annual figure since 2009.

Consumption itself has been sluggish. On Friday, the Commerce Department said U.S. retail sales fell 0.2 percent in March. The disappointing figure followed a downwardly revised 0.3 percent drop in February that marked the biggest decline in nearly a year.

The S&P 1500 retailing group closed Thursday within 2 percent of its all-time high hit this month.

“Even though it looks as though the Retailing Group has performed well over the last few years, practically all of the gains in the sector are the result of Amazon.com (AMZN), Home Depot (HD), and Priceline.com (PCLN),” the Bespoke note said. “Outside of these three stocks, the vast majority of the group’s members have been trending the other way.”

Bespoke actually created a portfolio for clients to track the losses by stocks most vulnerable to Amazon’s growing influence. The equal-weighted “Death By Amazon” index hit a four-year low on March 24.

Amazon.com itself hit an all-time high on April 5 and closed within 5 percent of that high on Thursday. U.S. markets were closed Friday for the Easter weekend.

Source: Bespoke Investment Group

The most shorted retail stocks, with short interest of more than 40 percent of shares available for trading, were luxury furniture seller RH (formerly Restoration Hardware), Rent-A-Center, Big 5 Sporting Goods, Fred’s and Dillard’s, Bespoke said.

J.C. Penney had short interest of 35 percent, Abercrombie & Fitch had short interest of nearly 30 percent and Nordstrom had short interest of almost 24 percent, according to the note.

Except for RH, all the above stocks are lower this year.

To be sure, Bespoke pointed out that short interest in the retail stocks was much higher during the financial crisis — close to 20 percent.

A Wells Fargo Securities survey of more than 500 people published April 10 showed more millennials prefer mall stores than nonmillennials, but that off-price was the top destination for just over half of both age groups.

— CNBC’s Krystina Gustafson and Reuters contributed to this report.