Media Democracy Action Fund is the lobbying arm of the Media Democracy Fund (MDF), an advocacy organization for left-of-center technology and communications policy.
The Media Democracy Action Fund is a project of the Sixteen Thirty Fund, the lobbying arm of the nonprofit network managed by the for-profit left-leaning consultancy Arabella Advisors. MDF is housed at the New Venture Fund.  MDAF is set up in a way to prevent institutional and other donors from having to disclose their contributions, leading critics to characterize it and the other Arabella advocacy outfits as “dark money” organizations. 
The Media Democracy Action Fund and the Media Democracy Fund played roles in helping to draft the “net neutrality” regulations enacted by the Federal Communications Commission under the Obama administration in 2015.  The regulations were supported by a number of left-wing advocacy groups including Media Democracy Action Fund, Free Press, and Fight for the Future, as well as major technology content provider companies including Google’s parent company Alphabet and Netflix. 
In 2018, the FCC under the Trump administration reversed the 2015 rules.