Shares of ConAgra Brands (CAG - Get Report) were lower by 3.64% to $39.44 on heavy trading volume on Tuesday afternoon, following a rating downgrade to "sell" from "neutral" at UBS. The firm set a price target of $35 on the packaged food company's stock, below its previous price target of $38.

The downgrade comes as UBS expects the stock's relative valuation premium will shrink due to a declining rate of margin improvement and little room for positive earnings estimate revisions, TheFly reports. The firm also believes the company's portfolio is not in a good position for a consolidating merchandise set.

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