Already-thin grocery retail margins will get even thinner in the coming years, according to a new analysis.

Industry earnings before interest and taxes (EBIT) — currently at about 3 percent of net revenues — could shrink another .9 by 2023, Morgan Stanley analyst Simeon Gutman says in a recent article in Barron's.

Competition from big box stores and online startups and the investment needed to fulfill e-commerce orders are among the reasons for the expected changes, according to the story.

Based on retailers’ response to the rise of Walmart in the 2000s in the U.S. and the growth of hard discounters, Gutman says the cost of investments to remain competitive on prices will cut into gross margins by a cumulative .5 percentage point over the next five years.

Big chains will fare best in the future, Gutman says. According to his model, the top 20 retailers now have 83 percent of the market, up from 79 percent five years ago.