Wall Street rarely talks about its mistakes, but Citi Research admitted in a note to clients that it messed up with its call on Walmart this year.

Citi Research raised its rating for Walmart shares to buy from neutral, citing the company’s e-commerce progress.

“We sat on the sideline with this name in ’17, which proved to be a big mistake. Despite the stock’s run-up, we think there is even more to come, particularly considering HD and COST are trading at a premium to WMT,” analyst Kate McShane wrote in a note to clients Monday. “Our belief that its aggressive omnichannel strategy will continue to drive significant sales growth and WMT’s ecommerce operations are emerging as a true challenger to Amazon, both factors that could fuel further multiple expansion.”

Walmart shares are up 1.4 percent in Tuesday’s premarket session after the report.

The retailer is one of the market’s best-performing large-cap stocks so far this year, rallying 42 percent through Monday versus the S&P 500’s 20 percent gain.

The analyst raised her price target for Walmart shares to $117 from $106, representing 20 percent upside to Monday’s close.

— CNBC’s Michael Bloom contributed to this story.