M
From ACT Wiki
1.
Credit rating.
A suffix added to a credit rating to indicate that it applies to a money market fund (rather than to any other type of entity).
So for example "AAAm" would indicate a rating of AAA in relation to a money market fund.
2.
One million (1,000,000).
For example EUR 100m = EUR 100,000,000.
Sometimes written "M".
