"Number two, we don't recommend Regency because it has grocery-anchored exposure," he went on. This is now going to be a problem for many REITs that considered grocery anchors to be safe havens of sorts. "How safe is Kroger now?," Dijkum asked.
Shares of Kroger were falling around 12 percent by late Friday. Other grocery names like Sprouts Farmers and Supervalu also saw their stocks dip further into red territory.
"Grocery was perceived as being safer. Now it's like... if you don't have the best grocer, you are not safe," Dijkum added.
A lot of these REITs have grocery exposure, but the question now is to what extent and which grocers, he said.
Less-grocery-exposed REITs Acadia and Federal Realty, for example, which operate so-called street retail properties, saw their stocks trade off slightly Friday but not as much as their shopping center peers.
"What is unclear is what the Amazon strategy will be and how it will leverage this asset," Jeffereies analyst Daniel Binder wrote in a note to clients.
"With no investor calls planned, to our knowledge, investors, analysts, competitors and suppliers are left guessing what Amazon may do to evolve this business. One might argue that the stores will act as distribution points for more same-day delivery and pick-up and this will probably be done in a more cost effective fashion than the current Amazon model."
It's no surprise, Amazon has been in the food business for more than 10 years, Binder went on.
The digital company's decision to enter the brick-and-mortar space is a "pretty big deal," and "suggests stores are in fact important and not just some defensive point of view that traditional brick-and-mortar players have taken," he added.