Most of the upside for Wal-Mart's stock is now behind it after its big run this year, according to Goldman Sachs.
The firm on Monday lowered its rating for Wal-Mart shares to neutral from buy, citing valuation.
In a note to clients, analyst Matthew Fassler wrote that Goldman downgraded Wal-Mart because of the company's "progress in growing earnings while investing in its business has been recognized by the market, as the stock's multiple has surged."
Shares of Wal-Mart were down more than 1 percent in Monday's premarket. Through Friday, they were up 41 percent this year versus the S&P 500's 15 percent return.
Fassler noted the retailer's forward price-to-earnings multiple is 21 times, which is a 15 percent valuation premium to the S&P 500.
"From here, though, the stock looks fairly valued," he wrote. "Benchmarked vs. global peers, even on our new, higher numbers, the stock does not offer value for its underlying growth."
The analyst raised his 12-month price target for the retailer to $100 from $91, representing 3 percent upside to Friday's close.
Wal-Mart declined to comment.
— CNBC's Michael Bloom contributed to this story.