The global rating agency says the lower ratings are due to its revised cross-sector methodology.
Shares of the Dow component fell 3.3% in pre-market trading.
The ratings agency downgraded its long-term deposit and senior unsecured debt ratings from A1 to A2.
The annual Trafficking in Persons (TIP) report said Myanmar slipped backward on its trafficked person's index to Tier 3 for failing to protect Rohingya Muslims fleeing a military crackdown in Rakhine state.
Like other European economies, Germany's expansion slowed at the start of 2018, adding 0.3% between January and March compared with 0.6% in the previous quarter.
The negative outlook reflects the high degree of uncertainty over the next 12 months associated with passenger growth for Malaysia Airports’ subsidiary, Sabiha Gokcen International Airport, in Turkey.