The Neenah, WI-based company is manufacturer of packaging products.
The lower rating is based on valuation, BMO said.
"Bemis has enjoyed a solid run this year and is trading at the upper end of its valuation range and in line with our price target. We remain impressed by the turnaround at Bemis and are encouraged by the transformation in corporate culture. However, valuation looks full at the moment," the firm wrote in an analyst note.
Big challenges for the company include organic volume growth and finding accretive acquisitions that strengthen its core franchise, the firm added.
BMO remains optimistic about the ongoing corporate turnaround and is monitoring the situation carefully.
Shares of Bemis closed at $52.58 on Wednesday.
Separately, TheStreet Ratings Team has a "Buy" rating with a score of B+ on the stock.
This is driven by several positive factors, which should have a greater impact than any weaknesses, and should give investors a better performance opportunity than most stocks covered.
The company's strengths can be seen in multiple areas, such as its solid stock price performance, good cash flow from operations, growth in earnings per share, notable return on equity and largely solid financial position with reasonable debt levels by most measures.
The team believes its strengths outweigh the fact that the company shows low profit margins.
Recently, TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.
You can view the full analysis from the report here: BMS