The firm initiated Micron at outperform and a price target of $62, above the $53.86 average target of analysts surveyed by Bloomberg.
It was more tempered in its assessment of AMD, opening coverage with a neutral rating and a $36 target, also the price-target average of $33.17.
Advanced Micro shares fell 0.5% to $35.96 a share, while Micron, despite the outperform rating, dropped 2% to $47.69.
The drops in Advanced Micro and Micron come amid a larger debate among analysts and other observers about whether the semiconductor industry has finally bottomed out amid a current down cycle, or still has some distance to go.
On the side of the bulls, Rosenblatt Securities last week hiked its price target of AMD to $52 a share from $42. At the time that was the highest target of any analyst surveyed by FactSet covering the stock.
"The setup for the company is for continued momentum into 2020 on broad-based desktop and server 7-nanometer deployments, continued 12-nanometer notebook traction (7 nanometer next year), and a new game console cycle that is a bit stronger than we have been modeling," wrote Rosenblatt analyst Hans Mosesmann.