HP's stock price dropped 1.83% to $18.75 after Bernstein lowered its rating on the tech company's stock to market perform from outperform.
HP's printing unit faces "greater structural headwinds" thanks to the shift to digital, according to the Bernstein report.
The analyst report also questioned whether HP can maintain the recent, strong showing by its PC unit given the growing threat posed by tariffs stemming from the trade war between the United States and China.
Bernstein cut its price target on HP to $20 a share, down from $25 previously.
HP saw a 5% decline in revenue from its printing unit in the third quarter. Even so, HP "outperformed the market in an increasingly challenging environment," outgoing CEO Dion Weisler told investors on an earnings call last month.
"HP continues to lead the Print category with a sharp focus on innovative products and services," Weisler said.
By contrast, HP's personal computer unit, whose growth rate has been questioned as potentially unsustainable by analysts at Bernstein, saw revenue jump 6% in the latest quarter and its profit margin surge by 51%.