Morgan Stanley & Co. analyst Toni Kaplan downgraded Moody's Corp.'s stock rating to "underweight" from "equal-weight," and lowered the price target to $135 from $143.

The company's shares are expected to face a hard time in this more challenging debt issuance environment. According to Kaplan, Moody's, being a more cyclical stock, has greater downside risk.

The analyst expects the company's ratings revenue to decrease by 1% in 2019.