Wall Street analysts are throwing shade at Pfizer's deal with Mylan, saying it will hurt profits through 2020

Morgan Stanley downgraded the company to "equal-weight" from "overweight" and moved its price target to $40 from $48.

The merger "exposes lower-than-expected earnings" for both Upjohn and RemainCo, Morgan Stanley analysts said. The bank anticipates 15% lower earnings per share in 2020, citing increased regulatory pressure, lower margins for RemainCo, and weaker Upjohn revenue.

UBS held a "neutral" rating for Pfizer shares with a price target of $43 before news of the spin-off. The bank continues to review the deal's specifics and has not yet announced its post-merger outlook.

Pfizer's split with Upjohn may be two-to-three years too late, as off-patent drug business has only continued to contract, a UBS analyst note said. The deal's first impression "does not suggest much to be excited about," the bank added, with weakness expected to continue beyond Tuesday's stock drop.